These databases are the best bets for finding secondary sources (also sometimes called scholarship, criticism, research) on literature. You'll want to find articles that are peer-reviewed (also sometimes called "academic," "scholarly," or "refereed") or that are books or chapters from books that are edited.
While most articles in these databases will be peer-reviewed, not all of them are. In most of these databases, you can limit your results to "peer-reviewed articles" or just "articles". You'll want to avoid "reviews" and "dissertations" because they are not peer-reviewed. If you are unsure, ask your instructor or a librarian.
To find books, choose the "books only" link and enter your search term. This link searches what UNM has and what other libraries have. This is useful because you can order these from interlibrary loan via the "request it" link. Books are almost always sent through the mail (*not* as an e-book), so plan on at least 10 business days.
For this class, you'll want to make sure your research from books has been edited. Here are some general guidelines to help you determine if it is an edited edition. If you're unsure, ask your professor.
To find out this information, click the "View description" link in the book record. Examples are below.