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The literature of a subject is the foundation of information sources. It represents a record of achievements of human race. Literature is diverse, complex and multilingual in nature. It is becoming more and more interdisciplinary and is growing at very fast pace. Literature serves the informational needs of various kinds of users and in turn it forms the sources of information.

Traditionally speaking, sources of information include primarily - books, periodicals, patents, standards, encyclopaedia, and newspaper. However, the number and forms of sources are continuously increasing. Even unpublished sources are becoming increasingly important to scholars. Occasions will come, when information would be required by a user without pre-condition about the form of document.

We may broadly classify the sources of information into; Documentary sources and Non documentary sources. Documentary sources can be categorized as primary, secondary and tertiary sources on the basis of appearance of information. In primary sources information appears first, secondary sources comes out next and tertiary sources are the last to appear. The Non-documentary source comprises of formal and informal sources. Formal sources includes information of research organizations, societies, industries, government departments, universities, consultants,. . .etc. Informal sources includes human sources, conversation with colleagues, visitors attendance at professional meetings, . . .etc.


The beginning of information sources may be traced to man's earliest attempts to record thoughts, concepts, ideas, and events. The visual may be said to have originated when man first sketched the outline of an animal that he wished to hunt. As he returned to look again at his sketch he became aware of an important fact, that the sketch had the power to refresh his memory of his original concept. With that awareness, the concept of information sources information its most rudimentary form may be said to have arisen. Other precursors soon followed the visual.

Early man recorded routes to good hunting and finishing areas, and maps began. Man recorded his accomplishments, and bibliographic sources arose. The " Gilgamesh Epic", for example (completed about 2000BC), tells the story of a legendary Babylonian King and the biblical flood. Prototype of almanacs could be observed information ancient Egypt. The Nile, endless, pulsating, throbbing with life! A sources of life, but unpredictable! The Nile overflowed its banks; the Egyptians recorded the event. The Nile overflowed again, and the phenomenon was recorded once again. As the years progressed, the Nile continued to overflow, and the man continued to record the event.

By comparing the records and overflowing of the Nile, Egyptians noticed a correlation between the two and eventually found a pattern information the timings of floods. They began to refer to the records for the records for prediction of events, and another type of source; namely' almanacs' arose. Compilation of a run of these almanac-type records eventually enabled ancient Egyptians to predict the Niles overflow.

An almanac, bibliographical sources, maps and early reference sources recorded a great deal of information. Eventually, man yearned for a single work that would synthesize the information in these varied sources, and the principle underlying encyclopaedias was born. From it came Encyclopaedias , such as the works of Aristotle , Varro and Pliny the Elder; and reference books may be said to have their historical beginnings in these works , since these texts still exist , at least in fragments.



It may be broadly defined as the various sources consulted for pinpointed and reliable information. These sources are broadly categorized as Documentary and Non-documentary sources and they are categorized as follows:-












Primary sources of information are the first published records of original research and development or description of new application or new interpretation of