If your research question is relevant to a particular state, you can start with the jurisdiction to find relevant secondary sources.
Westlaw: Select the "State Materials" tab on Westlaw's homepage just under the search bar, then click on the state of interest. Click on the link under "Secondary Sources" to view "All [STATE] Secondary Sources."

Lexis: Select the "State" tab on Lexis's homepage under the search bar, then click on the state of interest. Scroll down past the primary law (cases, statutes and legislation, administrative codes and regulations) and look under the "Secondary Materials" section.

Suggested California Treatises and Practice Guides: