Reference tools (once called reference books, when they were primarily dead-tree editions) is a resource "containing comprehensive information about a subject or range of subjects, esp. one intended for research or consultation on specific matters rather than continuous reading." (OED, "Reference Book") Examples are encyclopedias, dictionaries, atlases, handbooks, etc.

Articles from reference books are not usually cited in academic writing (because their content is so boiled-down), except for particular factoids. Instead, look for reference works that cite their sources and go to those sources. Narratives in encyclopedias/dictionaries/etc. are seen as more authoritative when articles are signed and have bibliographies.