Think of the recommended sources as pieces of evidence that support your argument, but also as a timeline describing types of sources to gather and use from start to completion of your first draft.
1. Explore topic & primary sources (news or non-library sources)
2. What's happened so far? Learn the background (WorldCat Discovery: books)
3. Newer research. Scholarly conversations (library databases: journal articles)
4. Support your argument (source citation)
5. Rinse, repeat; drafts & revisions (research librarians, writing center)