This page provides answers to some of the most frequently asked library science questions received by the Library, as well as answers to other common questions about the Library's online collections and services. The questions are divided into several topic areas, which you can choose from below.
The American Library Association External, the national library association of the United States, maintains a number of Fact Sheets External that address other questions about libraries and library science questions frequently asked by librarians and library students.
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The Library of Congress provides access to some digitized books on its website and the websites of partner institutions. These typically are older publications published prior to 1926 that are no longer under U.S. copyright protection.
For details on how to access the free e-books available through the Library, please consult our Finding E-books research guide.
There are numerous organizations that provide access to full-text books online, though at present most free online books tend to be older materials no longer covered by copyright. Some publishers provide electronic versions of contemporary books, but unless you are able to access them through an e-book platform available at your local public or university library, there is usually a fee involved.
To identify major online resources for accessing and downloading e-books, consult the Library's Finding E-books research guide.
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There are several Library of Congress numbers which users often conflate. They are:
Library of Congress Control Number (LCCN)
A Library of Congress Control Number (LCCN) External is a unique identification number that the Library of Congress assigns to the catalog record created for each book in its cataloged collections. Librarians use it to locate a specific Library of Congress catalog record in union catalogs such as WorldCat External and, in the past, used it to order catalog cards from the Library of Congress or commercial suppliers. The Library of Congress assigns this number while the book is being cataloged. Under certain circumstances, however, a card number can be assigned before the book is published through the Preassigned Control Number Program. Please note that not all books that receive an LCCN are cataloged by the Library or added to its collections.
What is now known as the Library of Congress Control Number was originally known as the Library of Congress Card Number until the advent of machine-readable records for book materials in the late 1960s.
An LCCN can have one of two different structures, based on when it was assigned:
In addition, LCCNs for some items cataloged before 2001 may include an alphabetic prefix:
In the Library's online catalog, LCCNs are reformatted to remove hyphens and standardize character length. For more information, see the online catalog's Help pages.
Library of Congress Call Number
A Library of Congress call number is a unique number assigned to items in the Library's collections that represents the item in the Library's online catalog, identifies the specific copy of the item in the collections, and gives its relative location on the shelf. Library of Congress call numbers are assigned by Library catalogers based on the the Library of Congress Classification (LCC) system.
Copyright Registration Number
A unique number assigned to all works registered with the U.S. Copyright Office at the Library of Congress. The copyright registration number is typically formatted as two or three letters (depending on the classification) followed by one to seven digits. Examples include:
Preassigned Control Number
A Preassigned Control Number (PCN) is a Library of Congress Control Number (LCCN) which has been "preassigned" to a given work prior to the work's publication. Works are assigned a PCN through the Preassigned Control Number Program. Please note that obtaining an LCCN for a book through the PCN Program does not guarantee that the book will added to the Library's collections or listed in its online catalog.
International Standard Serial Number (ISSN)
The International Standard Serial Number (ISSN) External is an eight-digit number which identifies all periodical publications as such, including electronic serials. Most countries have an ISSN National Center responsible for assigning ISBNs to serials. In the United States, ISSNs are assigned by the U.S. ISSN Center at the Library of Congress.
Users sometimes confuse the following numbers with a Library of Congress number:
International Standard Book Number (ISBN)
The International Standard Book Number (ISBN) was approved as ISO standard 2108 in 1970. It is a 10- or 13-digit number that uniquely identifies books and book-like products published internationally. The Library of Congress does not assign ISBNs to books. Instead, there are over 160 ISBN Agencies worldwide, each of which is appointed as the exclusive agent responsible for assigning ISBNs to publishers residing in their country or geographic territory. The United States ISBN Agency, R. R. Bowker External, is the only source authorized to assign ISBNs to publishers supplying an address in the United States, U.S. Virgin Islands, Guam, and Puerto Rico, and its database establishes the publisher of record associated with each prefix. Review the ISBN FAQ External for further information.
Universal Product Code (UPC) Number
Also known as a bar code. The UPC number is a string of digits that typically appears on the back of books (and other consumer products). The UPC number appears in association with a machine-readable code that appears as a series of black and white strips or bars. In the United States, UPC numbers are assigned to products by the organization GS1 US External. An overview of the UPC can be found on the Bar Codes Talk website External.
The Library of Congress classifies books according to the Library of Congress Classification (LCC) system. An outline of LCC is available on the Library's website, as is the complete text of the classification schedules.
The Library of Congress Classification (LCC) consists of 21 main classes, each class represented by a letter of the alphabet. Because only 21 classes were required to represent the major subject areas and disciplines classified by the Library, five letters were not included as part of the LCC. The reason that the particular letters I, O, W, X, and Y were not selected for the LCC is a matter of some debate. There are few extant records that document the development of the LCC, and it appears that none which survive discuss why these letters remained unused.
Despite the lack of documentation, an oral tradition passed down through generations of Library of Congress catalogers accounts for the exclusion of these letters from the LCC. This tradition holds that the letter I was not used because it is too similar to the number 1; use of an I class would cause confusion for people looking for works which had a call number such as I1, I10, and I111. Similarly, the letter O was not selected because it is indistinguishable from the number 0 (zero). W, X, and Y, as the final letters of the alphabet (not including Z), were never needed since there were only 21 classes. Had there been a 22nd class, perhaps W would have been the next letter used, and if there had been a 23rd class created thereafter, perhaps X. The letter Z was chosen as a class rather than W, X, or Y in part because it is the symbolic end of the alphabet. In addition, the Library's Class Z is based upon a Class Z (Book Arts) developed earlier by Charles Ammi Cutter for his Expansive Classification system. Somewhat ironically, Class Z was the first Library class created, prepared in 1898 by Charles Martel.
A number of libraries have created guides and videos designed to help users understand how to read Library of Congress call numbers. A selected list of online learning resources are provided below:
A Preassigned Control Number (PCN) is a Library of Congress Control Number (LCCN) assigned as part of the Preassigned Control Number Program. As part of the PCN program, a LCCN is "preassigned" to a given work prior to its publication. For further details, see the PCN program FAQ, "What is the difference between a Library of Congress Card Number, a Library of Congress Control Number, and a Preassigned Control Number?"
Publishers participating in the PCN Program are obligated to send a complimentary copy of all books for which a Preassigned Control Number (PCN) was provided immediately upon publication. Once the Library of Congress receives a print copy of the book, it will be considered for addition to the Library's permanent collections. Please note that not all books submitted to the PCN Program are selected for the Library's permanent collections. Final determination of works selected and cataloged for the Library is made by selection librarians and recommending officers in compliance with Library of Congress collection development policies upon receipt of the printed book.
Many books that receive an LCCN through the PCN Program are self-published or independently published. These categories of books, especially literary works that fall under these categories, are not likely to be selected for the Library's permanent collections. Please review our supplementary collection policy guidelines for "Independently Published and Self-Published Textual Materials" to learn more about he types of self-published materials the Library is likely to add to its collections.
On January 1, 2007, the book industry began using 13 digit ISBNs to identify all books in the supply chain. The U.S. ISBN Agency noted ahead of the transition External that this change was effected to "expand the numbering capacity of the ISBN system and alleviate numbering shortages in certain areas of the world," and "to fully align the numbering system for books with the global EAN.UCC identification system that is widely used to identify most other consumer goods worldwide."
An ISBN-13 differs from an ISBN-10 through the inclusion of a three-digit prefix (978 or 979) and a different check digit (final digit) at the end. Conversion tools are available External to convert ISBN-10s to ISBN-13s (and vice versa) and to calculate an ISBN's check digit. Please note, however, that ISBN-13s beginning with the prefix 979 have no ISBN-10 counterparts.
The Library of Congress online catalog automatically converts between ISBN-10s and ISBN-13s, ensuring that any ISBN search will check for both an ISBN-10 and an ISBN-13. For example, if a catalog record includes only an ISBN-10, a search for the equivalent ISBN-13 will retrieve the record.
Several extensive book databases allow users to retrieve bibliographic information based on an ISBN search. None of these databases is comprehensive, however. Examples of proprietary databases that allow retrieval of bibliographic information for books based on ISBN are the subscription database Books in Print and the database freely available online through the commercial vendor Amazon.com External (see its Advanced Search page External). To see if it is possible to configure the information in these databases for your needs, and to obtain permission to do so, you will need to contact and obtain the permission of the vendor.
While the Library of Congress generally cannot provide technical support services for individuals creating their own catalogs or databases, the Library of Congress online catalog allows users to search for and retrieve catalog records based on ISBNs. If you would like to use the information in the catalog to develop a Web-based application that captures bibliographic information based on an item's ISBN, the Library supports a Web service that allows users to retrieve catalog records in XML. In order to take advantage of this service, known as SRU (Search/Retrieval via URL), users must have the ability to display the XML data in the format they desire. Below are some examples of SRU requests that retrieve the same record from the Library's catalog (via its Z39.50 interface). The final two examples make use of XSLT style sheets created by the Library. Users can also develop their own style sheets and retrieve the raw XML records using requests similar to the first one listed below.
SRU Request Examples
Please note that the Library of Congress online catalog does not include a record for every book published in the United States. Furthermore, not every book receives an ISBN. A number of other libraries' catalogs are also available using the Z39.50 protocol. Many are listed on the Library's Z39.50 gateway.
Another solution is to use a batch search facility that allows Library of Congress catalog records to be exported into a desired format, or provides you with a tool set that you can use to create style sheets to perform the desired conversion. Two such batch search facilities (which are both present in Z39.50 clients) are:
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There is no comprehensive resource or database that you can check to locate a book's Library of Congress classification (LCC) number or Library of Congress (LC) call number. The best place to begin your search is the Library of Congress online catalog. When you open a record for a book in the catalog, look for a field labeled "LC Classification . If this field is listed, it will give the book's LC classification, as below:
Please note that a partial classification may consist of a book's class number (the first assigned letter, e.g. P), subclass (the first two assigned letters, e.g., PN), or subclass plus a 1-4 digit division number (e.g, PN1021).
You will not always find an LC classification number or LC call number for a book through the Library's online catalog. This often is because the online catalog does not include a record for every book ever published. In addition, some records for recent works are incomplete and have yet to include a book's LC numbers.
To find a book's Library of Congress classification number or call number when it is not available through the Library's online catalog, try using OCLC's WorldCat database External. WorldCat functions as a collective catalog of thousands of libraries around the world. A subscription version of WorldCat is available at some public libraries and many academic libraries, while a free version is available on the Web at https://www.worldcat.org/ External. The subscription version of WorldCat will often provide the Library of Congress classification number for a book, and both the subscription and free versions list libraries known to hold copies of a book. Search the catalogs of the academic libraries that WorldCat lists as holding a copy of a book to see if any have assigned the book an LCC. The numbers may vary slightly from one library to another based on local guidelines and standards, but they will give you an idea of the LC classification numbers (and LC call numbers) that libraries have assigned to a specific book. If you are cataloging a book, you can use or adapt one of these numbers to suit your local needs.
Another option for locating a book's LCC is to search a database developed by OCLC known as Classify External. Classify is designed to support the assignment of classification numbers for books, DVDs, CDs, and many other types of materials. Using Classify, you can identify a work by title, author, ISBN, LCCN, UPC, or OCLC number. The record that is returned will include the LC classification (as well as the Dewey classification) most commonly assigned to that work by WorldCat member libraries. LC call numbers are not provided through Classify.
There is no comprehensive resource or database that you can check to locate a book's Dewey Decimal Classification (DDC) number or Dewey call number. The best place to begin your search is the Library of Congress online catalog. When you open a record for a book in the catalog, look for a field labeled "Dewey Class No." If this field is listed, it will give the book's DDC number, as below:
Dewey call numbers (a call number consists of a classification number plus additional numbers or notation that distinguish items with the same classification number from each other) for books and other items are not available through the Library of Congress.
Not every book cataloged by the Library includes a Dewey Decimal Classification number. The Library's Dewey Program participates in the Cataloging in Publication (CIP) Program by assigning a DDC number to every CIP record. Because the CIP Program limits eligibility to titles that are most likely to be widely acquired by the nation's libraries, the Dewey Program directly serves those libraries. The Dewey Program also assigns Dewey numbers to books in English, French, German, Italian, Portuguese, and Spanish.
To find a book's Dewey call number, or a book's Dewey Decimal Classification number when the DDC is not available through the Library's online catalog,try using OCLC's WorldCat database External. WorldCat functions as a collective catalog of thousands of libraries around the world. A subscription version of WorldCat is available at some public libraries and many academic libraries, while a free version is available on the Web at https://www.worldcat.org/ External. The subscription version of WorldCat will often provide the Dewey class number (the first part of the Dewey number) for a book, and both the subscription and free versions list libraries known to hold copies of a book. Search the catalogs of the public libraries that WorldCat lists as holding a copy of a book to see if any have assigned the book a Dewey Decimal Classification number or a Dewey Decimal call number. The numbers may vary slightly from one library to another based on local guidelines and standards, but they will give you an idea of the Dewey numbers that libraries have assigned to a specific book. If you are cataloging a book, you can use or adapt one of these numbers to suit your local needs.
Perhaps the best option for locating a DDC is to search a database developed by OCLC known as Classify External. Classify is designed to support the assignment of classification numbers for books, DVDs, CDs, and many other types of materials. Using Classify, you can identify a work by title, author, ISBN, LCCN, UPC, or OCLC number. The record that is returned will include the Dewey Decimal classification (as well as the LC classification) most commonly assigned to that work by WorldCat member libraries. Dewey call numbers are not provided through Classify.
A subscription database known as Classification Web provides correlations between Dewey and Library of Congress classification numbers, as well as between these call numbers and Library of Congress Subject Headings. You can check with your local library to see if it has access to this database.
A print resource which provides a similar function, though not as comprehensively, is the 3rd edition of Mona L. Scott's 3-volume Conversion Tables (v. 1, LC-Dewey; v. 2, Dewey-LC; v. 3, Subject Headings-LC and Dewey).
A very general classification conversion tool is available through archived help page for OCLC's former reference management service, QuestionPoint. See the following two pages:
These pages note that "mappings to LCC classes D, J and K are still in process. LCC Class R has been replaced, in QuestionPoint, by National Library of Medicine (NLM) Classes QS-QZ and W. Most NLM Classes map to 362.1-362.3 and 610-618.97."
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The American Library Association's "Setting Up a Library" External resource guide compiles print and online resources for individuals interested in organizing their libraries. See especially the sections on small and home libraries External and church and synagogue libraries External.
Additional ideas for cataloging church libraries can be found through the Evangelical Church Library Association External. For other suggestions on cataloging home libraries, see the March 2019 Inside Book Riot article "8 Home Library Apps to Keep Your Book Collection Organized External."
For an overview of library automation issues, see the American Library Association's Fact Sheet Number 21, "Automating Libraries and Virtual Reference: A Selected Annotated Bibliography External," which "offers a selection of articles, treatises, and web resources that will provide an introduction to the issues to consider when moving from the card catalog to the computerized catalog, or upgrading from one present integrated library system (ILS) to another, or considering implementing virtual reference services."
Library Technology Guides External, prepared by Marshall Breeding (Jean and Alexander Heard Library, Vanderbilt University), includes a database of library automation companies you can use to find companies that develop and market library automation systems.
Every May, American Libraries magazine publishes a review of the current library automation marketplace. The most recent review, published in May 2020, is "2020 Library Systems Report External."
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MARC records for books, periodicals, and other materials in the Library's collections can often be found through the Library of Congress online catalog. Once you open a record for an item in the catalog, check the top of the record for a tab labeled MARC Tags:
Click on the "MARC Tags" link to view the MARC record for the title.
If a MARC record cannot be found through the Library's online catalog, your next best option is to search other library catalogs to find a library that supplies a MARC record for the title. The best option for identifying a library that has a catalog record for a book is to search the WorldCat database External, a global library catalog that includes hundreds of millions of records contributed by libraries around the world. You can search WorldCat to locate a record for a title External for which a MARC record is needed. Once you locate a record for the title in question, enter a zip code or other location into in the "Enter your location" box and click "Find libraries," which will return libraries that should hold a copy of the title in question. (Note: you may need to choose the "Select libraries holding just this edition" link to limit your search to a particular edition.) Scroll down the page to view the list of holding libraries. At this point, you can click on the name of a library to open its catalog record for the book; or, if that option is not available or does not work, click on the "Library Info" link at the right of the library listing to search for its online catalog, and then conduct a search for the title within it. Once you open the catalog record for the title, check it to see if a MARC record is also available.
Another option for locating MARC records for titles is to search the library catalogs listed on the Z39.50 gateway page. The library catalogs available through the Z39.50 interface can be searched specifically for MARC records. To conduct a MARC record search, open the catalog search page for any institution, and in the top field labelled "Select Preferred Record Display" choose "Tagged" as the display type. The catalog search you conduct will then display MARC tags/records for all results.
If you are unable to locate a MARC record for a title through the Library of Congress online catalog, WorldCat, or the Z39.50 gateway, you may need to contact a local library to see if a cataloger there can assist you with generating an appropriate record.
Although searches of OCLC's WorldCat database External and the Library of Congress online catalog retrieve many records listed in the print editions of the National Union Catalog External, a number of records are still unavailable. A September 2008 article in College & Research Libraries, "The Proportion of NUC Pre-56 Titles Represented in the RLIN and OCLC Databases Compared: A Follow-up to the Beall/Kafadar Study External" (PDF, 362 KB), estimated that 25% of NUC Pre-1956 records were not listed in WorldCat. (Read the 2005 Beall/Kafadar study External.) It is unlikely that WorldCat has reached 100% inclusivity in the intervening years, making a search of NUC an important supplement to WorldCat.
In addition, due to the manner in which the retrospective conversion of the Library's old card catalog to online form was undertaken, NUC Pre-1956 continues to include some entries for works in the Library's collections not listed in the Library's online catalog. Consequently, it should be consulted in any thorough examination of the Library's resources.
All 754 volumes of National Union Catalog, Pre-1956 Imprints are now digitized and available online through the HathiTrust Digital Library External. Its catalog record includes a table of contents for the set that can help librarians and researchers select the appropriate volumes to search. A standalone table of contents is also available on the Library of Congress website.
During June 2013 the Library of Congress announced that it was transitioning to online-only publication of its cataloging documentation. The printing of new editions of subject heading and classification documentation has now ceased, and all new editions and updates are now freely available on the Library' Cataloging and Acquisitions home pages. Information about the status and location of selected LC cataloging documentation follows below. View the Cataloging and Acquisitions home page to locate other documentation, such as Library of Congress Classification Outline, MARC standards, authority records, and more.
LCSH and LCC remain available through Classification Web External, LC’s online subscription service. Classification Web is a fully searchable and browsable interface for accessing the most up-to-date headings and classification numbers in LCSH. Its features include correlations between subject headings and classification numbers and vice-versa, and a direct search of LC and other library catalogs.
The SHM and CSM continue to be available through Cataloger’s Desktop, LC’s subscription-based online documentation service. Cataloger’s Desktop provides browsing and keyword searching of over 300 cataloging and metadata resources. It is updated quarterly.
There are several ways to access and search Library of Congress Subject Headings online. First, the Library's Acquisitions and Bibliographic Access Directorate website makes available print-ready PDF files for the current edition of the Library of Congress Subject Headings (LCSH), as well as older editions back to the 34th edition (March 2012). This online set constitutes an updated digital edition of the now-discontinued print editions (the "Red Books") of LCSH.
LCSH also are freely accessible through the Library of Congress's Linked Data Service. LCSH in this service includes all Library of Congress Subject Headings, free-floating subdivisions (topical and form), Genre/Form headings, Children's (AC) headings, and validation strings for which authority records have been created. The content includes a few name headings (personal and corporate), such as William Shakespeare, Jesus Christ, and Harvard University; and geographic headings that are added to LCSH as they are needed to establish subdivisions, provide a pattern for subdivision practice, or provide reference structure for other terms. This content is expanded beyond "the big red books" (the older, paper editions of LCSH) with inclusion of validation strings. This service allows users to conduct a keyword search for subject headings, and offers individual and bulk downloads of records.
Because the keyword search option available through the Linked Data Service version of the headings does not return reference terms ("see," "see also," or "used for" terms), searching it for authorized subject headings may prove difficult for some users. Consequently, users trying to identify authorized subject headings may prefer to search the Library of Congress Authorities database. This database returns reference terms allowing users to quickly identify correct subject headings (e.g., a search on "Sickness" will return a "see" result referring users to the authorized heading "Diseases").
Authority Records available through the Authorities database include those for:
Authority Records are not available for:
Finally, the Classification Web database External (subscription required; available at many academic libraries) provides enhanced access to the most recent edition of the LCSH.
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The Library of Congress has explored and taken advantage of the Internet's potential for sharing the Library's content with remote users since the early 1990s. The following timeline highlights significant moments in the history and development of the Library's presence online. Some links in the timeline lead to archived versions of Library pages no longer available on the Library's website. These archived pages are available through the Library of Congress Web Archive and can be recognize through their URLs, all of which begin https://webarchive.loc.gov/. In addition, all quotations in the timeline are from the article "The National Digital Library and the Library's Electronic Resources" in the Encyclopedia of the Library of Congress.
The Library of Congress is often asked to estimate the amount of data represented by its physical and digital collections. Usually, the specific figure sought is the amount of data, in terabytes, if all material in the Library were converted to digital files. The Library of Congress has never officially released such a number, nor even attempted such a calculation. Writers of various publications and advertisements, however, have frequently attempted to generate such a number, resulting in the circulation of unofficial figures stating that the Library holds anywhere from 10 to 50 (or more) terabytes of data.
The Library of Congress does not provide an official estimate of the amount of data represented by its collections because an accurate answer would constantly change and is subject to too many variables. Even when limiting one's consideration to the conversion of materials to digital formats, an accurate estimate would depend on numerous factors:
Any answer would also need to consider non-book materials. The Library of Congress holds millions of audio and video recordings, three-dimensional objects, manuscripts, maps, drawings, prints, photographs, printed music, and other non-book items.
In an April 15, 2010, press release, the Library's Office of Communications notes that "the Library holds more than 167 terabytes of web-based information, including legal blogs, websites of candidates for national office and websites of Members of Congress." In addition, Matt Raymond, former Director of Communications at the Library of Congress, provided an overview of how much data the Library's physical and digital content represents on the Library of Congress Blog. Mr. Raymond notes that, as of February 11, 2009, "the approximate amount of [the Library's] collections that are digitized and freely and publicly available on the Internet is about 74 terabytes. We can also say that we have about 15.3 million digital items online."
Please note that where Mr. Raymond mentions "15.3 million digital items online," he means, more specifically, files. A single Library item can consist of multiple files, and the ratio between the numbers of catalog records, physical objects, and digital files that represent a single Library item can vary considerably, depending largely on the type of physical objects and how they have been cataloged, scanned, and presented on the Library's Web site. Here are some examples to illustrate this point:
A July 11, 2011, post on the Library's digital preservation blog The Signal blog includes additional thoughts on attempts to measure the size of the Library's collections in terabytes.
A March 23, 2012, post on The Signal titled "How many Libraries of Congress does it take?" cites a number of instances in which the size of the Library's collections is compared to other projects. An August 6, 2012, post, "The Immeasurable Library of Congress," discusses the importance of the materiality of objects in the Library's collection, and why the size of the Library's collections is less important than the work of stewardship. A January 15, 2014, post titled "A Half Century of Library Computing," reproduced in the March/April 2014 issue of Library of Congress Magazine (p. 5), describes the Library's current IT infrastructure:
The Library's current information technology (IT) infrastructure includes five data centers in four building locations. These facilities support more than 650 physical servers, 400 virtual servers, 250 enterprise systems and applications, 7.1 petabytes of disk storage and 15.0 petabytes of backup and archive data on tape. The Library's IT infrastructure also includes a wide-area network, a metropolitan-area network and local-area networks that comprise 350 network devices. The Library's Information Technology Services Office also supports more than 8,600 voice connections, 14,700 network connections and 5,300 workstations.
The reference to "7.1 petabytes of disk storage" indicates only potential storage space, however, and not necessarily the amount of Library content currently stored on disk.
A contract for the Library's first ILS was awarded on May 15, 1998, to Endeavor Information Systems, Inc., for its Voyager integrated library system. On October 1, 1999, the Library successfully completed initial implementation of all modules of the ILS, including cataloging, circulation, acquisitions, serials check-in modules, and the online public access catalog.
In November 2010, the Library upgraded its ILS to Voyager version 7.2.0 from Ex Libris. Its previous ILS upgrade occurred in May 2008, when it upgraded to Voyager version 6.5.2.
As part of the Library of Congress update for the American Library Association 2021 Midwinter Virtual Meeting, the Integrated Library System Program Office (ILSPO) noted the following:
ILSPO successfully implemented Voyager 10.1.0 to provide new functionality for all of the Library’s Voyager production databases and catalogs. ILSPO coordinated the project with OCIO, Copyright, the Congressional Research Service, the Cataloging Distribution Service, the Law Library and NLS along with OCLC, the British Library and SkyRiver. ILSPO staff collaborated with OCIO to package and deploy more than 40 workstation applications.
ILSPO also noted its future plans:
The next generation Library Collections Access Platform (LCAP) will modernize the systems that provide access to the Library’s collections. ILSPO delivered the requirements traceability matrix; issued the Library’s Request for Information; analyzed the responses from vendors; conducted market research; and submitted a New or Expanded Program Request for a fiscal 2022 budget request to support LCAP.
For further, primarily historical, information about the Library's Integrated Library System, see the Library's ILS Program Office Web pages, including its background page, and FAQ page. Contact ILSPO directly for further information about the Library's ILS.
The Library of Congress's website launched at the American Library Association (ALA) annual conference in Miami on June 22, 1994. Several months later, on November 7, the Library implemented its first digital reference service, the National Reference Service (NRS). This pilot project was an email-based service through which the Library received patron reference questions through a centralized email address, [email protected] (no longer active). While designated Library staff responded to inquiries through the [email protected] email account, many of the questions submitted through the service were referred by NRS to email accounts maintained by other areas of the Library.
The NRS pilot project was a success, and during the summer of 1995, the National Reference Service established a new email address, [email protected] (no longer active), as the centralized address for online inquiries to the Library. By the summer of 1996, the NRS averaged 850 email questions per month. About half of these inquiries were referred to other email accounts at the Library. The NRS remained in operation until 1999, when it was incorporated into the Library's Humanities and Social Science Division (now the Researcher and Reference Services Division) and renamed the Reference Referral Service.
While the National Reference Service functioned as the Library's digital reference service during the late 1990s, the Library was also exploring other opportunities for expanding its online reference services. Of particular note, during June 29-30, 1998, the Library held a two-day conference, "Reference Service in a Digital Age External." This conference grew out of discussions among reference librarians the previous January at the American Library Association Midwinter Meeting about how the growth of the Internet was affecting their work. The conference was hosted by Diane Kresh, Director for Public Service Collections at the Library, in cooperation with Anne Lipow of the Library Solutions Institute of Berkeley, California. Participants discussed the challenge of "remote" users, the difficulty of training staff to adapt to a rapidly changing digital environment, and the potential for developing collaborative and innovative responses to these challenges using available technologies as a starting point.
Emerging out of this conference, and through a series of follow-up meetings and discussions at various professional gatherings, came the idea for the Collaborative Digital Reference Service (CDRS). The Library began to build CDRS in the Spring of 2000. Remedy, a help-desk software, was "broken and rebuilt" by the Library's in-house programmers to function to the specifications agreed upon by members of the group. The new software had three main components: a database of library profiles describing a library's services and its collection strengths, an automated "Request Manager" which would route a question automatically to the member of the network "best-suited" to answer it, and finally, a Knowledge Base, a database of Questions and Answers which could be used as a resource for members of the network. Although the software was developed originally by the Library of Congress, starting in 2001 it was further developed through a partnership between the Library and OCLC (The Online Computer Library Center of Dublin, Ohio, USA).
Libraries participating in CDRS could submit reference questions they received to a “Global Reference Network” (GRN) of participating libraries. The metadata assigned to the question by the referring library would be checked against a database of profiles established by participating libraries; the question would then be routed to the library identified as best match for the question based on criteria such as the question's subject; the patron's education level; and the current availability of participating libraries to answer the question.
The first live question was submitted to CDRS on June 29, 2000. During the initial testing phase, the Library of Congress partnered with sixteen other libraries: Santa Monica (Calif.) Public Library; Morris County (N.J.) Public Library; Suburban Library System (Chicago area); Peninsula Library System (San Mateo County, Calif.); Metropolitan Cooperative Library System (Los Angeles area); AskERIC; the National Library of Canada; the National Library of Australia; the Smithsonian Museum of American Art; Cornell University; the University of Minnesota; the University of Texas at Austin; Vanderbilt University; the University of Washington; EARL: The UK Public Library Consortium; and the University of Southern California. By May 2001, 100 libraries and institutions External were participating in the project. The number grew to more than 250 by the end of the year.
An extensive history of CDRS, along with articles documenting the launch and development of the project, can be found on the Library's archived "Global Reference Network" Web pages.
In January 2002, as the scale of CDRS began to exceed the ability of the pilot software to function smoothly, the Library of Congress signed a second collaborative agreement with OCLC to develop what became known as QuestionPoint, The QuestionPoint digital reference management software (view archived OCLC pages about QuestionPoint External) enabled users to submit questions to the Library through Web forms and a chat tool. QuestionPoint's web forms were the first online reference forms implemented by the Library that could be completed directly by patrons (CDRS forms were completed by librarians). These forms were available through the Library's "Ask a Librarian" service home page. (The Library branded its digital reference service "Ask a Librarian" in 2001).
As QuestionPoint gained traction, the volume of email inquiries received by the Library's Reference Referral Service decreased. On April 2, 2004, the service was abolished and its staff were reassigned to other units within the Humanities and Social Sciences Division.
By 2005, the Library's Ask a Librarian service had been adopted by all Library public reading rooms except the Copyright Records Reading Room. Each reading room had its own QuestionPoint account and was responsible for handling the questions submitted to it. The questions were (and still are) either answered by staff in that reading room, or else referred to another area of the Library, or a specific Library employee, best able to answer the question.
Prior to QuestionPoint's launch the Library had experimented with a pilot chat service, offered from October 11 to November 12, 2001, using 24/7 Reference software. The Library's QuestionPoint-based chat service launched on July 10, 2002. The service operated from 2-3 p.m. ET, Monday through Friday, and during its test period was staffed by librarians in five reading rooms. For most of 2002 until September 2020, two areas at the Library offered chat: the Digital Reference Team (incorporated into the Researcher and Reference Services Division in 2015) and the Newspaper and Current Periodical Reading Room.
The Library's chat service was, and remains, local. Although QuestionPoint supported a robust "24/7 Reference Cooperative" through which member libraries provided mutual chat coverage and service, the Library decided not to participate in this program. The Library continued to participate in the web-form based "Global Reference Network," referring questions to, and receiving questions from, other GRN members. However, the volume of GRN questions, remained relatively low, and GRN use among libraries diminished greatly after its first several years of operation. If they weren't already doing so, many GRN members turned to providing shared reference coverage through the live chat service available through the 24/7 Reference Cooperative. The GRN was eventually discontinued.
At this time, the Library's chat service is offered Monday through Friday, noon-4 p.m. ET, by its Researcher and Reference Services Division and its Newspaper and Current Periodical Reading Room, which staff separate chat queues.
The digital reference software currently used by the Library of Congress is LibAnswers External. The Library switched to the LibAnswers platform after QuestionPoint was sold External to Springshare, which owns LibAnswers External, in May 2019. The Library officially began using LibAnswers on August 24, 2020.
The Library has general guidelines for the provision of its digital reference service. The most recent guidelines are not available online. An older, and now outdated, set of guidelines from 2003 is the "Library of Congress QuestionPoint User Guidelines."
Since 2003, the Library of Congress has received tens of thousands of questions each year through its Ask a Librarian service. The Library's Reference Correspondence Policy broadly outlines the types of services it can and cannot provide to patrons through the service. While the policy states "correspondents are encouraged to use local and online resources," the Library makes every attempt to respond to all questions it receives, even in cases where patrons may not first have consulted their local or academic library. In other words, the Library does not require that patrons first contact their local library, or that a question work its way up through a system of local and regional libraries before reaching us as the library of "last resort" that can address the question. The Library welcomes digital reference questions from anyone, anywhere, at any time.
If you have further questions about the history of digital reference at the Library of Congress, please contact us through Ask a Librarian.
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The Library of Congress does not explicitly indicate whether a book is poetry or prose in its catalog records. You can review the Library of Congress Subject Headings (LCSH) assigned to a book to see whether a word such as poetry or biography, which might help indicate the form of the book, is given. Bear in mind that a subject term such as poetry is typically used to designate a prose work about poetry (e.g., a collection of essays), and not a work of poetry itself. The Library of Congress Classification cannot be used to determine whether a book is poetry or prose; however, a book's Dewey Decimal number, which is often available through Library catalog records, will sometimes indicate the form of a book's content. Once you learn a book's Dewey number, you can review the heading describing the topic that the number represents through the Dewey Decimal Classification Summaries External. For instance, the following numbers for American and British literature help to indicate whether a work is poetry or prose:
811 American poetry in English
813 American fiction in English
821 English poetry
823 English fiction
Other options for determining whether a book is prose or poetry include checking the physical book, especially its back and front covers, spine, copyright page, and dust jacket, to see if the publisher has included a designation of poetry or a nonfiction genre; consulting book reviews, articles, and other publications about the work to see if they mention its format; checking the book publisher's or author's website to see if it indicates the form of the book; contacting the book's publisher (contact information is usually available through the Web); and contacting the book's author (through his or her publisher, an official website or social networking page, or other means).
The Library receives many questions about whether a work is poetry or prose from Texas students and teachers participating in University Interscholastic League (UIL) oral interpretation competitions External. An excellent UIL document that assists with this process is "Defining and Distinguishing Poetry, Prose, and Drama External." The UIL's FAQ page External and other areas of its website discuss appropriate and inappropriate forms of documentation for contests and who to contact for an official ruling in uncertain cases.
If you'd like to receive the Library's help determining whether a book is poetry or prose, please contact us through Ask ask a Librarian.
Library of Congress catalog records do not always provide a definitive answer to whether a work is fiction or nonfiction. Ascertaining whether a book is fiction or nonfiction through the Library's online catalog is usually performed through review of the Library of Congress classification number assigned to a book. To find the classification number assigned to a book, you can search the online catalog to find a record for the book in question, then click on the Full Record tab and review the field labeled LC Classification. (You should also review any Library of Congress Subject Headings listed on this page, as they may provide a designation of fiction.) Literature is classified under the letter P, but there is wide variation on whether something in Class P is fiction or nonfiction. If you find that the Library of Congress classification number starts with PZ, that is definitely fiction. PR and PS (English and American Literature, respectively) can be used for works of fiction, as well as works of nonfiction such as literary criticism, essays, biographies of authors, etc. You would need to look at the full classification number and at a very detailed classification schedule for help in determining if it is fiction or nonfiction, and this may not be conclusive. The Library often is asked about works with a classification of PN: sometimes these are collections of wit and humor. In this case, the Library of Congress classification will not designate whether the work is fiction or nonfiction, and it may be necessary to use other means to make a determination.
To see whether other Library classes identify a work as fiction or nonfiction, you can check class numbers against the descriptions of them given in the Library of Congress Classification Outline. For instance, for a book classified as HV, one can use the classification outline to learn that this is a designation for social sciences and the work is, therefore, nonfiction.
A book's Dewey Decimal number, which is often available through Library catalog records, will sometimes indicate whether a book is fiction or nonfiction. Once you learn a book's Dewey number, you can review the heading describing the topic that the number represents through the Dewey Decimal Classification Summaries External. For instance, the following numbers for literature indicate the work is fiction:
813 American fiction in English
823 English fiction
833 German fiction
843 French fiction
Other options for determining whether a book is fiction or nonfiction include checking the physical book, especially its back and front covers, spine, copyright page, and dust jacket, to see if the publisher has included a designation of fiction or nonfiction; reviewing bestseller lists, book reviews, articles, and other publications about the work which may mention its genre; checking the book publisher's or author's website to see if it indicates the genre of the book; contacting the book's publisher (contact information is usually available through the Web); and contacting the book's author (through his or her publisher, an official website or social networking page, or other means).
The Library receives many questions about whether a work is fiction or nonfiction from Texas students and teachers participating in University Interscholastic League (UIL) speech and debate competitions External. Participants should explore the UIL's website, especially its "Oral Interpretation" External pages, which includes a "Helpful Checklist for UIL Prose Documentation Requirements External," "Helpful Checklist for UIL Poetry Documentation Requirements External," numerous rulings on valid forms of documentation, and more. See also the New Coach FAQ External to learn about appropriate and inappropriate forms of documentation for contests and who to contact for an official ruling in uncertain cases.
There is no central body that assigns books a reading level. Often, a book's reading level is determined by book publishers or by those with certain expertise such as reading/education specialists, young adult librarians, and school media specialists. In addition, there are many different standardized methods, often known as leveling systems, for determining the reading level of a book. For an introduction to leveling systems, see Linda Cornwell's “Nuts and Bolts of Book Leveling External.” An overview of several of the most popular leveling systems is Ruth Manna’s “Leveled Reading Systems, Explained External.” Additional resources on leveled reading are available on the Scholastic website External.
The Library of Congress does not endorse or apply a leveling system or any other method of assigning a reading level to books in its collections*; it defers to those who are experts in this area. Occasionally, the Library's online catalog records will include a link to a publisher's description of a book or a book review that mentions a book's reading level. To determine if a catalog record includes a link to a book review or publisher's description, you can open the record and look for the field labeled "Links." This field will include hyperlinks to all electronic resources, including reviews and publisher's description, available in the record.
A number of other websites provide access to databases or book lists that allow users to identify the reading level for a book. Users will need to review each website in order to ascertain which leveling system or method is used to determine books' reading levels. One resource that allows users to search a database of more 50,000 books for details on how the book rates according to different leveling systems is Scholastic's Teacher Book Wizard External.
*The only exception is the National Library Service for the Blind and Print Disabled, part of the Library of Congress, whose online catalog records sometimes include suggested grade levels taken from book reviews.
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There are several options for requesting books and other materials from the Library of Congress.
First, you may request print books through your local library's interlibrary loan (ILL) service. The Library of Congress does not loan materials to individuals, but does loan eligible books and other materials to other libraries on a case-by-case basis. These requests must be initiated through your local library. Generally, your local library will first attempt to request materials from another library before contacting the Library of Congress. The Library of Congress does not charge for this service; in some cases, local libraries charge a nominal fee for interlibrary loan. For additional information, consult the Library's interlibrary loan services Web pages.
Second, you may purchase reproductions of books and other eligible materials through the Library' Duplication Services. This is a fee-based service. The Duplication Services website includes ordering and pricing information, as well as a page for first-time users. Review the Duplication Services websites and contact Duplication Services directly to learn more about this possibility:
Library of Congress Duplication Services
101 Independence Avenue SE
Washington, D.C. 20540-4570
Telephone: (202) 707-5640
Fax: (202) 707-1771
E-mail: [email protected]
Web Form: https://www.loc.gov/duplicationservices/customer-service/contact/
Please note that all orders must be accompanied by the reproduction number, call number, or digital ID for each individual item (these numbers can be found in online catalog records and are often included in publications). If numbers are not found via these means, they must be identified through your research or by requesting research services in the reading room that has custody of the material.
Third, some older Library books may be digitized and available online. To learn more about how and where to access digitized Library of Congress books, please see the Library's Finding E-Books resource guide.
Finally, it may be possible for Library reference staff to provide you with single-page scans or reproductions of short articles or a limited number of items from our special collections as time and resources allow. Contact the Library's Ask a Librarian service with your request, specifying the specific item you would like scanned or copied, to see if your request can be fulfilled. Please note that if an item is still protected by copyright, Library staff may not be able to provide you with a copy.
For materials that you are unable to obtain through the Library of Congress, contact your local library about the possibility of borrowing or obtaining copies of the needed materials from another library.
The Library of Congress acquires books and other materials for its collections through a variety of means, including:
If you or your publisher has submitted one or more copies of your book to the Library of Congress through one of the options above, your book will be considered for addition to the Library's permanent collections. Not all books offered or submitted to the Library are added to its permanent collections, however. The selection of materials for the Library's permanent collections is made by Library acquisitions divisions and selection officers in accordance with the Library's collection policy statements. Generally speaking, self-published books and books published through independent publishing platforms are not added to the Library's permanent collections. Details about the types of self-published materials likely to be acquired by the Library are described in the supplementary collections policy document "Independently Published and Self-Published Textual Materials."
If you submitted or registered your book with the Copyright Office you will not be notified if your book has been added to the Library's permanent collections. Books added to the Library's permanent collections will be listed in the Library's online catalog. If you find a record in the catalog for your book, and the record's "Item Location" section includes a call number and location for the book, it was added to our permanent collections. If you don't find a record for your book in the Library's online catalog within two years of submitting it to the Library—the Library can take a year or longer to process and fully catalog books added to its collections—then your book was almost certainly not added to the Library's collections.
If a book's author or publisher never submitted a copy of the book in question to the Library of Congress, then the book is unlikely to be held by the Library. Authors or publishers can pursue the most appropriate acquisition option from the list above in order to have their books considered for addition to the Library's permanent collections.
Yes, the Library supports a number of portals and websites that celebrate the histories and contributions of American citizens from different cultures and backgrounds. The Library's current monthly portals, through which you can discover digital collections, rich stories, and special events made available by the Library and other federal cultural heritage institutions, include:
There are several databases you can search to locate copyright registration and renewal records online. The only official, authoritative databases at this time are those available through the U.S. Copyright Office at the Library of Congress. The other resources listed below represent the work of individuals and organizations not affiliated with the U.S Copyright Office at the Library of Congress.
These databases will not always provide definitive information on the copyright status of a work. Further information on researching the copyright status of works can be found through the following resources:
Contact the U.S. Copyright Office directly if you need additional copyright research guidance.
The Library of Congress's Teachers page offers guidance on how to cite primary and secondary sources on the Library of Congress website. The examples are based on style guidelines commonly used in history (The Chicago Manual of Style External) and language arts (MLA style External) disciplines.
Examples of how to cite materials from the Library's American Memory collection A Century of Lawmaking for a New Nation are also available online, as is more general guidance on formatting legal citations.
In addition, many bibliographic records (e.g., https://www.loc.gov/item/wpalh000034/) for items from the Library's digital collections now include a "Cite This Item" link through which you can find suggestions for citing the item according to Chicago, MLA, or APA style.
You should consult the current official edition of the documentation style being used for authoritative information on how to cite materials according to that style (consult a local librarian to identify the current edition of a particular style manual). One website that includes helpful information on generating appropriate citations in a variety of different styles is the Purdue Online Writing Lab External (Purdue University)
Many electronic databases available through libraries now provide automated suggestions for citing materials according to several documentation styles. Consequently, be sure to check entries in electronic databases to see if they include suggested citations. Many databases also allow users to export citations into reference management software External that facilitate the creation and organization of bibliographic citations. These include:
While the functionality of reference management software varies, most allow users to create and extract citations not only from database entries, but also from a host of primary and secondary sources, including books, articles, Web pages, audio recordings, video recordings, and legal documents.
Additional information about reference management tools and citation guidelines can be found on the "Citations & Formatting" page of Using the Library of Congress Online: A Guide for Middle and High School Students.