Reference works contain collections of information. Reference works are things like dictionaries, encyclopedias, bibliographies, and atlases. Wikiepdia, as an encyclopedia is also a reference work.
Generally, reference works are not cited in academic projects but are used to find other resources that you might want to cite. From reference works, you can find key words related to your topic to use in your searches in the library catalog/website. You can also sometimes find lists of references in the reference work that you could consult to find more information.
