Scholarly journals publish articles that report the results of research.
There is often an emphasis on the theoretical aspects of a field of study. Articles are submitted to an editorial board and are critically evaluated via the peer review process before publication. There is a great effort to maintain the highest academic standards within scholarly journals. When a college professor assigns students to locate articles, it is generally expected that the students will use journal articles. If you are not positive what types of materials to use for the assignment, check with your professor.