Periodicals play a unique role in the distribution of information and library research.
Any subject found in books can also be found in periodicals. Periodicals publish the most recent concepts, opinions and research before appearance in books is possible. Some materials never appear in book form. Some topics are so transitory or so specialized that only small groups have an extensive interest in them. Many subjects must be supplemented by periodical literature or newspapers to bring facts up to date or provide a variety of opinions and discussions.