Knowledge is of two kinds. We know a subject ourselves, or we know where we can find information on it. — Samuel Johnson
Reference : a work (such as a dictionary or encyclopedia) containing useful facts or information — Webster
Reference work is a work, such as a book or periodical (or their electronic equivalents), to which one can refer for information. The information is intended to be found quickly when needed. Such works are usually referred to for particular pieces of information, rather than read beginning to end. The writing style used in these works is informative; the authors avoid use of the first person, and emphasize facts. Reference works include dictionaries, encyclopedias, almanacs, atlases, bibliographies, biographical sources, catalogs such as library catalogs and art catalogs, concordances, directories such as business directories, discographies, filmographies, glossaries, handbooks and manuals. — Wikipedia
Worlds of Reference (Tom McArthur)
You could look it up: the reference shelf from ancient Babylon to Wikipedia (Jack Lynch)
A Reference Guide To Reference In You Could Look It Up (Genevieve Valentine, NPR)
Reference Librarianship in Star Wars
Jedi Master ‘Madame’ Jocasta Nu
Here are links to pages about closely related subjects.
2. Some of the information on this page as well as the classification scheme used for the resources on all of the pages on Cosma was initially developed in the year 2000 while Mary E. Hopper was taking a course entitled LS407 Reference/Information Services at the Simmons Graduate School of Library and Information Science. It was a legendary, very rigorous course taught by Dr. Allen Smith.