Reference work

The writing style used in these works is informative; the authors avoid opinions and the use of the first person, and emphasize facts.

Updated editions are usually published as needed, in some cases annually, such as Whitaker's Almanack, and Who's Who.

Reference works include textbooks, almanacs, atlases, bibliographies, biographical sources, catalogs such as library catalogs and art catalogs, concordances, dictionaries, directories such as business directories and telephone directories, discographies, encyclopedias, filmographies, gazetteers, glossaries, handbooks, indices such as bibliographic indices and citation indices, manuals, research guides, thesauruses, and yearbooks.

Wikipedia, an online encyclopedia, is both the largest and the most-read reference work in history.

Because some reference books are consulted by patrons too frequently to have enough copies and others so infrequently that replacing it would be difficult, libraries prefer to make them available for photocopy rather than checkout.