A subject-specific encyclopedia (or encyclopedic set) is a single (or multi-volume) reference work that provides background information on a more specialized discipline.
While Wikipedia can be a great place to start to learn the vocabulary of an unfamiliar topic area, a subject-specific encyclopedia is even better. Try some of the examples below, or search ti:("encyclopedia of") AND nt:(reference) plus your area of interest as a quick-and-dirty way to find out if there is a subject encyclopedia you can use in the Reference Collection.
Encyclopedia of Homelessness by