Scholarly journals will publish some types of articles that are not peer reviewed or based on research.
Remember that not every article in peer reviewed journals is a peer-reviewed research article.
Often times the editor of a journal will write an article with his or opinion or summary of the article. This can lead you to good sources but are not appropriate for most research papers.
These provide insight or opinion on new books. Though book reviews are written by experts, these articles are not considered scholarly and should not be used for your research papers. These are useful to let you know whether or not you should use the book it reviews