This part of the research process can be tricky for some, as the researcher devotes some attention to non-academic sources. Peer-reviewed (i.e., scholarly sources) are wonderful publications to consult in the context of needing scientifically written, well-vetted information. All academic information should be credible, but not all credible information will be peer-reviewed.
Even so, a credible publication will have undergone some vetting process. A magazine such as Time or Popular Mechanics will have an editorial process in place to approve the pieces their journalists submit. The quality of periodicals will often vary in part based on how rigorous that process is. Without Peer-Review Process in place, as an academic publication would have, magazines can't be counted as a scholarly source. That does not mean such a publication is not credible, it simply means that it cannot fulfill the academic portion of the research process.