Book excerpt: The Subject Approach to Information is a highly readable, comprehensive study of information retrieval methods. For the fourth edition, Professor Foskett has revised and and updated his work to include current developments in all aspects of information storage and retrieval by the subject approach. The theme of the work is the basic similarity of all methods of information retrieval, and the problems which need to be solved in order to obtain good results from any system. The book opens with a consideration of the theory of information retrieval systems and explores both the difficulties and the potential of using computers in this field. The problems and uses of the different pre-coordinate and post-coordinate systems and languages are studied in depth, and there is a close examination of computer-based systems, including videotext and text retrieval, as well as more conventional reference retrieval systems such as DIALOG and Euronet/DIANE. A final chapter describes and discusses a selection of significant evaluative studies in information retrieval.