Since periodical publications are now a major information disseminating media, the work of the Periodical Publications Section assumes great magnitude and importance in libraries of universities, research institutions and other learned bodies. They, however, form one of the "sources of perplexity" in library work. "Their vagaries may transcend all imagination arid anticipation. It looks as if nothing relating to a periodical publication can escape the sport of caprice-publishing society, name, periodicity, format, pagination, excrescential attachments to all story volumes and, last but not the least, the span of the lives and resurrection", says Ranganathan. In other words, the kinds of complexities pertain to - irregularity in volume - number, irregularity in publication, change of title and sponsor, amalgamation, splitting, supplement, etc. For details regarding each, the reader is referred to Ranganathan's Classified Catalogue Code. These vagaries not only create problems to the cataloguer but also break the back of the Periodical Section which is entrusted with the task of acquiring periodicals. In addition, if the non-receipt of a particular issue is not brought to the notice of the publisher, the chances of the library getting it later are rather slim.
A brief description of different types of periodicals and sources of information helpful in building a periodical collection are discussed in Units 5 and 6 respectively.