Resources for this class include Reference works for background information, Biographical resources for information about individuals, links to the USMAIcatalog for finding books, and databases of theatre, performance, and literary criticism for scholarly articles.
Basics: the theater style /period under consideration is Commedia dell'arte . Whether you are searching for background information, books, or articles you can use that exact phrase for either keyword or subject searching in the catalogs and databases. Keyword searching (use parens around the phrase: "Commedia dell'arte") is a broader search and will return more results, subject searching is more focused and will return fewer results. You can combine the term with other word/phrases to focus on distinct facets of the topic.
Background information: use the term as given or search by individual names. Try Oxford Art Online for chronology, overviews, and additional resources.
Biography: by personal name. Biography in Context , Artemis Literary Sources (which includes the Dictionary of Literary Biography) and the Oxford Dictionary of National Biography [English persons only] are all good resources for biographical information.