Tertiary sources compile, summarize, index, or help identify scholarly sources on a topic. They are useful for background research or to get an overview of a topic before delving into secondary or primary sources. Common tertiary sources for literature include dictionaries, encyclopedias, handbooks, and other reference sources. This page includes links to some best bets, but you can also search the library catalog for books that give an overview of your topic of interest.
The OED online can be used to perform simple searches for word definitions, or for full-text searching of all OED's definitions, etymologies and quotations through the Search function.