
Peer-reviewed (or refereed) articles are scholarly journal articles that have undergone a thorough review process by a group of experts in the same field prior to publication.
You can use the Ulrichsweb database to determine if a specific journal is considered peer-reviewed. If a journal is considered peer-reviewed, then any articles published within it would be considered peer-reviewed.
Also, many library databases allow you to limit your searches to only peer-reviewed materials. By selecting this option, the database should only show you results that are peer-reviewed.