What is a reference source?
Any publication from which authoritative information can be obtained, including but not limited to reference books, catalog records, printed indexes and abstracting services, and bibliographic databases. Individuals and services outside the library that can be relied upon to provide authoritative information are considered resources for referral (ODLIS, 2018).
A reference book is "designed to be consulted when authoritative information is needed, rather than read cover to cover."
Examples: almanacs, atlases, bibliographies, biographical sources, catalogs, concordances, dictionaries, directories,
discographies and filmographies, encyclopedias, glossaries, handbooks, indexes, manuals, research guides, union lists, yearbooks, etc.