There are different types of periodicals: popular, trade, and scholarly. So if you want to find scholarly articles, you need to make sure you are searching in scholarly journals or periodicals. Scholarly articles are also sometimes called peer-reviewed. Scholarly articles and journals are published by experts in their field as a way to communicate research in an open, accessible and transparent way and to keep a running account of research and thought related to a given topic. Peer-reviewed means that the article has been reviewed by other experts in the same field prior to publication.
There are a few clues that you are looking at a scholarly or peer-reviewed article. These are: