Before conducting a search, check and see if the online periodical database has an option to limit your search to scholarly or "peer reviewed"** publications. For example, there may be a box you can check that says "peer reviewed." While this is a good first step, you should be aware that each online database provider (e.g. EBSCOhost) may have different definitions of "peer reviewed."
What is peer-reviewed?
This term generally refers to a publication that contains only articles that have been reviewed, (qualified) edited and selected by recognized experts in the particular field of study covered by the journal.