Excerpt from Periodicals: January-December, 1971 The Catalog is subdivided into parts correspond ing to the classes of material listed in section 5 of Title 17 of the United States Code. The table at the end of this preface shows the organization of the Catalog, the symbols used with the registration numbers to identify the classes, and the prices of the semiannual or annual issues. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.