Classifying Secondary and Tertiary Information Sources : Secondary and tertiary sources are usually in the form of books or recorded materials which are commonly stored in libraries. In an attempt to overcome the problem of locating information, libraries have adopted a standard method of arranging publications so that information can be readily found. An example of a standard system is the Dewey Decimal Classification System. This consists of assigning an arbitrary number to broad areas of human knowledge. These large areas are then subdivided again and again so that the more subdivisions there are, the more precise is the definition of the subject.

In the Dewey Decimal System, the number 5 is ascribed to scientific subjects.

The system is then progressively sub-divided as shown in Figure.

SCIENTIFIC

(Area 5)

Figure: Dewey Decimal System for Science.

Books in libraries, therefore, are arranged in a numerical order. However, the great disadvantage is that the Dewey Classification number is assigned by a librarian who may be guided by the title rather than the content and thus assign an inappropriate number. If this happens it can be very difficult to find a particular book.

The Dewey Decimal System could be applied to some types of equipment classification. For example, a large collection of microscopes could be effectively indexed using the Dewey Decimal System.