As mentioned earlier, supply is another basic factor. Supply means availability of periodicals / serials for acquisition. Information regarding supply can be collected in the forms of various selectional sources or tools. A detailed discussion on a variety of selection tools, their characteristics, value and importance for selection of periodicals / serials is given in Unit 6 under sec. Selection Tools.
The selection tools which should be a pad of periodicals collection of directories; lists brought out by major indexing and abstracting services like Chemical Abstracts, Science Citation Index, Engineering Index; trade catalogues issued by individual publishers; current issues of important book trade journals; previews and announcements issued by publishers; union catalogues of periodicals; National Bibliographies; Reports of citation studies and Reports of User Need Surveys.
The selection of periodicals should also be governed by financial considerations. The finance available for periodicals will normally be decided by the library budget. Proper budgeting should take into account the amount needed to continue current subscriptions as well as the price increases which are not unusual in the case of periodicals. The amount set apart for the latter will have to be added every year. The selection of every new item is a commitment not only for the current year but also for succeeding years.