"Peer-reviewed journals" are scholarly. Most of your research should come from scholarly journals.
Want to know more? Watch a brief YouTube tutorial from Vanderbilt Univ. called Scholarly vs. Popular Periodicals.
Still not sure if your source is a peer-reviewed journal? Use the link below and search for the journal. HINT: Enter the journal name and specify that it be in the "TI Title" field. View the record for your journal and look for the "Peer-Reviewed" line. If it says "Yes," you're in business!