Digital documents as the real ones have to be classified and indexed in a library for proper future exploitation. Classification and indexation process is a hard one for librarians all over the world. A software system can ease their work and make the process more accurate. We present in our paper methods for classifying and indexing publications, suitable for such a system and analyze different storage and index database management systems capabilities in order to use them as support for classification, indexation and retrieval processes in an integrated software system for libraries. Furthermore, the problem of storing and retrieval of full content of a publication is taken into consideration.