A periodical is published more than once a year. The titles listed above are popular magazines. Of course, if you are just interested in reading an article on current happenings in the profession you can go to the library's current periodical section and browse through the titles. However, if you want to find articles on a topic, your most efficient approach is to use an index.
Indexes list articles by topic.
Choosing which index to use is your first decision. This question has several answers. This index has articles going back to the 1830s, and is updated daily online. The library has a license to access the Avery index for up to five simultaneous users. If you get a busy message, it may be that the maximum number of users has been reached.