The topics in the following list of Library of Congress subject headings link directly to the Online Catalog and automatically execute a search of the specified subject heading. Publications about commodities appear throughout the Library's collections. Works dealing with commodity industries are classed between HD9000-HD9999, while works about the science or technology related to growing, extracting or processing a particular commodity are found in classes S (agriculture) and T (technology). The classification range for commodity trade and investment are cataloged in the HG6024-HG6051 range, except for gold and silver (HG293-HG307), because of their use in monetary systems. Searching for a particular commodity by keyword, such as "corn" or "gold" and another term, such as "futures," is also efficient. Additional works in the Library of Congress may be identified by searching the Online Catalog under appropriate subject headings.