Background sources are useful for providing overviews. They may give historical context, or include bibliographies of works on a given topic. Types: encyclopedias, dictionaries, bibliographies.
Enter the scholarly conversation. Find out what other academics are writing about your subject, and use their opinions to complement or contrast with your own arguments.
Primary resources take advantage of direct experience - including your own! An artist's letters, a reviewer's of-the-time opinions, or your own experience of a performance all can be considered primary resources.
