The library catalogue is the main key to the library collection. The card catalogue for the books acquired by the library before 1990 is still in use; can be found in the ground floor of the Library. The Online Public Access Catalogue (OPAC) is available through the Library web page and user terminals in the library. It provides access to the book collection of the library acquired by the library since 1991 to date.The system of classification used in the Main library is a modified form of the Dewey Decimal Classification System.