You can Google the name of the journal in which your article was published.  On the journal website look at the ABOUT link, or the link for AUTHORS, or HOW TO SUBMIT.  Usually this will tell you if peer-review is part of the process before an article is accepted for publication.   Sometimes the information is right on the journal homepage

It depends on which database you are using. . .  

• If you are using the main SEARCH EVERYTHING box on the library homepage, you can use the filters on the left to check for peer-reviewed sources. 

• If you are using EBSCOhost databases (like Academic Search Premier) there is also a filter for scholarly or academic articles.

• If you are using SCOPUS or Science Direct, the research articles are from peer-reviewed journals, but some articles may not be research articles...they might be editorials, or letters to the editor. or other commentary.

• For other databases, check the descriptions (help) for what type of material is contained in the database.

• Still not sure? Email Askalibrarian@njit.edu