Information Sources - Definition

When it was identified that non documentary information gained from human as well as institutions could also be functioned as information materials, there was a need to find out a new term which could include non documentary information since the term ‘document’ is appropriate only for documentary information.  The new term information sources had become widely used terms in the library science literature. With an introduction of this new term, recorded information was, for the first time in history, classified according to the characteristics of the information rather than classifying them based on to the physical format of the materials. All the information sources were classified according to their content into three categories such as primary information sources, secondary information sources and tertiary information sources (Rajagobalan, 1983).