The most up-to-date information on a given topic is quite often published in periodicals-journals, magazines, newspapers or any other publication issued at regular intervals-rather than in books. A periodical index is a list of articles from a specific time period contained in a group of selected publications or that cover a group of related subjects. Organized alphabetically they may be searched by author, title and subject in the same manner as you would in a library catalog.
Often available in both print and electronic formats, periodical indexes include the source information-periodical title, volume, issue, and page numbers-needed to locate an article. Electronic indexes, often referred to as periodical databases, usually include more information on each article, such as abstracts or short summaries, than print-media indexes.