Library of Congress
Most call numbers for items in our collection are assigned using the Library of Congress Classification system, often abbreviated LC, which groups items by subject. The first letter in the call number tells you the general subject of an item, which can be useful if you want to browse a subject of interest.
U.S. Federal Depository Documents
Federal documents in our collection use a call number scheme called the SuDocs (Superintendent of Documents) system.
The call numbers on these documents represent the issuing agency and type of publication, not the subject. For example, PREX 2 represents the Office of Management & Budget, while PREX 3 includes publications from the Central Intelligence Agency.