JSTOR is a multidisciplinary database providing access to a wide breadth of scholarship including books, journals, and primary sources. For those of you searching for critical theories related to your angle of advocacy, I recommend giving this database a try. Its search functions are slightly different from the other databases we've covered, so here are some strategies to try:
Select Advanced Search (under the Basic Search box)
Further refine by searching against your initial set of results.
You may limit to journal articles by checking the "Journals" box; the vast majority of resources in JSTOR are peer-reviewed, including books. However, if you are unsure, check the source of your article (Journal name) and the publisher by doing a simple Google search. If you're still unsure, reach out to a librarian or your professor.