If someone has already done research on a topic you are investigating you are encouraged to seek out the same sources. Sometimes you may find an abundant amount of material that wasn't important to them, but is perfect for you. Other times you may find you disagree with their interpretation, which will give you something to write about from a fresh perspective.
Theses and dissertations are a great place to find bibliographies (sometimes called literature reviews) Many can be found in this database-
How do you find out which of these journals has articles on your specific topic?
Use a database to find out.