Reading Call Numbers The Library of Congress arranges materials by subject, or 'class'. The first section of the call number represents the subject of the book. The second section often represents the author's name, and the last section is the date of publication.

You can search catalog records by keyword or browse by authors/creators, subjects, names/titles, series/uniform titles, and call numbers. Browse lists also include searching aids such cross-references and scope notes.

The LCCN number differs from the ISBN number in that an ISBN is assigned to each edition or format of your book while the Library of Congress number is assigned to the work itself. This is a two-step process and can take anywhere from one to two weeks to complete.