A state-specific law encyclopedia (e.g., the Maryland Law Encyclopedia)
can be a good starting point for a research problem set in a specific
General coverage law encyclopedias (American Jurisprudence 2d
or Corpus Juris Secundum) can provide general background and
citations to primary authorities from various states.
The state series of A.L.R. (3rd - 5th) may contain an annotation
on your topic. A print index covering the third through fifth series
is available, or A.L.R. can be searched on Westlaw.
Many treatises or the Restatements of Law can provide analysis and
citations to state case law.
Law reviews can sometimes be found dealing with the law of specific
states. Lexis and Westlaw provide databases that cover legal periodicals
published by law schools in individual states; search these with some
caution because they frequently include only a few publications. Also
helpful are multi-state survey articles in law reviews which help identify
trends and put the law of your state in perspective.