Your instructors will specify if they want you to cite academic sources. If you are unsure whether your instructor will accept popular sources as well, please ask. In order to properly cite a source, you need to identify its publication type. In a college database, you won't have a cover to judge an article by, so you'll need to know that journals usually have the word "journal" in the title of their publication; for example, Journal of Criminal Justice.
Periodicals are published at regular intervals. The chief difference between scholarly, also called academic or peer-reviewed, articles and popular sources is the amount of time an article spends being edited and reviewed. Newspapers come out every day; academic journals, two or four times a year. In short:
Scholarly vs. popular sources
Instructors asking you to use credible sources may also use Turnitin.com to evaluate your citations to see whether you use scholarly, academic or peer-reviewed, or popular. See the box below to determine whether a source is "scholarly" or "popular."