In HerdSearch, use the facets to the left, or look at the information about the article to see if it is peer reviewed.
In EBSCO databases, use the limiters at the left to narrow your results to peer-reviewed only:
ProQuest databases offer you a couple of options:
And some databases contain nothing but peer reviewed work like JStor and Project Muse.
NDSU librarians are always available to help if you have questions about an article you found.