LCSH publishes microfilm, microfilm, computer tapes and CD-ROMs, and printed copies. Starting from the twelfth edition 1989, the titles added and deleted in each edition are printed separately and arranged between the preface and the main table for easy reference. The preface of LCSH introduces the classification statistics, brief history of development, title structure and model title list of each edition. The main table is arranged alphabetically by many standardized titles and various references, and many titles are followed by the classification numbers of the Library of Congress Classification. The appendix is a bibliography list of children's books. LCSH is the largest and most widely used bibliography in the world, which plays an important role in the development history of retrieval languages and the subject cataloging of libraries today. The Library of Congress published the Subject Cataloguing Manual (Title Part) from 1984, and from 199 1 to the fourth edition. It is the most important auxiliary tool for using LCSH. Besides introducing the basic provisions of subject cataloging, it also introduces various subheadings and their usage in a large space.