When searching for materials related to Poland and Polish history in the Library of Congress Online Catalog and in other repositories, there are several strategies and to keep in mind.
Authorized subject headings can be useful when searching in online catalogs. Subject headings include standardized topics, names, places, titles, and forms/genres of material. Subject headings like those listed below can help researchers get started and to perform searches in the Library of Congress Online Catalog.
When searching in the Library of Congress Online Catalog, you can confine your search results to materials held by the Manuscript Division using "advanced search" (see screenshot below).