Non-documentary sources of information from a substantial part of communication especially in science and technology. User’s studies have underlined importance of such sources. These sources provide information which other sources do not. There are two kinds of sources
- Formal sources of information,
- Informal sources of information.
1. Formal sources include research organizations, societies, industries, government departments, universities, consultants, etc.
2. Informal sources include conversation with colleagues, visitors, attendance at professional meeting, etc. Very often, the conversation or discussion would point out primary or secondary sources. Informal sources are live sources, which are extremely important in the process of communication. Very often, if a scientist working on an experiment needs some data, he would turn to the catalogue working in the same laboratory rather than consult a printed page. Informal sources tend to be more convenient sources because it is currently easier to have a dialogue with an expert than use a bibliography or index or card catalogue or even consultation of a reference librarian. The documents essentially are monologues but a dialogue with a human being can assist in classifying one’s requirement for information.