Full-text magazines across a broad range of subject areas.
The above link will help you differentiate between primary and secondary resources. You should strive to reference primary resources when making your own inferences on a subject. Secondary sources can be used to compare or contrast your findings.
Not all periodical publications are created equal. Scholarly publications are peer-reviewed and should be your first choice for accurate and in-depth information. The above link will help you select appropriate periodical sources.