Search in Secondary Sources
When secondary periodicals are available on the subject as well as on the broader subject, the search must first begin with the secondary periodical on the subject proper, supplemented by references collected from the periodicals covering the broader subject. Usually, the secondary periodicals covering broader subjects would cover peripheral journals and some times quite alien to the main subject of search. But it is a well-known fact that there is a considerable scatter of information on a given topic over a whole range of periodicals covering core, peripheral and alien fields. Although a few core journals cover a considerable part (50-60%) of the published literature on a given topic, yet sizeable portion (30-40% or more) can be covered by scanning a large number of peripheral journals in alien fields (e.g., an article of medical interest, say malaria eradication, may be published in a sociology journal). Skills are to be developed for the consultation of secondary periodicals, since a wide variation is observed in the pattern of the arrangement of the entries as well as in the methods of indexing, and also the types of indexes provided. Usually, the. indexing method used is explained in the introduction to the index. Pertinent subject headings vary from one secondary periodical to another. The searcher should acquaint himself not only with the scientific nomenclature and terminology, but also with the popular and trade names.