You will need to incorporate a minimum of three scholarly sources into your research essay. As is the case with evaluating sources broadly, standards for considering a source "scholarly" vary across disciplines.
However, there are a few rules of thumb that you can use to identify scholarly sources in literary studies:
1. The source is written by an expert in the field. Look up the author of the source. What are their credentials? Do they hold an advanced degree in literary studies or a related field?
2. The source has citations. A scholarly source will always cite other scholars' work.
3. The source is published in a peer-reviewed journal or book. To verify peer-review status, search the name of the journal or publishing house along with "peer review process."