Periodicals: the word periodical, refers to magazines or journals. The word serial is also used to describe a magazine or a journal as well as a newspaper. Periodicals are good sources for contemporary or current information. There are different types of periodicals, for example there are scholarly journals and there are popular magazines and they have different purposes. Example.

Periodical Indexes: are special resources that refer you to periodical articles that contain information you need. Until about 1980 most periodical indexes were books (print indexes); you would look up your topic by subject heading for a list of citations to periodical articles. Most periodical indexes today are computer databases.