You will usually be expected to find scholarly articles in academic journals -- specifically, in what are called "refereed" (or "peer reviewed") journals. This means that the articles have been reviewed ("refereed") by experts in the field, and that these experts have judged the articles to be worthy of publication.
In a database such as Historical Abstracts, most of the results you get will be peer-reviewed articles. However, you can be certain of whether or not you are finding refereed articles by selecting "Peer Review" from the list of search refinements that is available on the left sidebar of every results page.
Using the library search on the home page of the library, you will find many more results that may not be refereed. Therefore, it will become even more important to select the "Scholarly & Peer-Review" search refinement on the left sidebar of the results page.
All digital resources listed here are by SMU subscription (login required from off-campus). Databases provide indexing and full-text access to journal articles, newspapers, books, audiovisual works, and more.