Bibliographies: Look for bibliographies at the end of scholarly journal articles (or at the end of books). If you find an article that is right on-topic, odds are that the author has ALREADY done most of the same research that you need to do. Use the author's list as a starting point for your own research.
Cited Reference Search: A cited reference search is a great way to find related research. You can search an authors bibliography, as noted above. You can also see whose cited the author thereby tracking research done more recently. A great tool for this is the Web of Science database.