You may have heard the word periodical before. Many sources that we use in both academic research and our personal lives are periodicals. A periodical is a resource such as a journal, a magazine, or a newspaper that is published multiple times a year. Periodicals are designated either by date of publication or by annual volume numbers and issue numbers (based on the number of issues published in a given year).

Peer-reviewed scholarly journals are of course periodicals, but most periodicals are classified as popular rather than scholarly. The articles in Rolling Stone (a periodical with a focus on politics and popular culture published twice each month) do not go through the peer-review process like the articles in scholarly journals. Lack of peer review does not disqualify magazines as possible legitimate sources for your research, unless your assignment specifically requires all sources to be scholarly articles or books. Look back at Figure 8.1 for a breakdown of different types of sources.