Companions and handbooks are excellent sources to find an overview of a topic, an explanation of unfamiliar terms, or brief factual information on authors, plots, genres, etc.
Bailey/Howe Library subscribes to many electronic scholarly subject-specific encyclopedias, companions, and dictionaries from two publishers: Gale and Oxford University Press. In addition to searching each title individually, you may search across all the titles in each publisher's aggregated database. The library owns many, many more subject-specific print and online encyclopedias, companions, and dictionaries. Ask a librarian for help in locating these.