This volume contains important material not found in the original edition: an index to printers and publishers. It also contains addenda and corrigenda to the 1926 edition, and to the first two volumes of the second edition. The new Printers' and Publishers' Index has headnotes 1) giving each individual's dates of activity, 2) supplementing and in many cases correcting information in the Bibliographical Society's Dictionaries of Printers, and 3) listing addresses of British publishers in far more complete and accurate detail than available previously. There is a second index, entirely new, of places of printing other than London, including fictitious places. The addenda and corrigenda are cumulative, incorporating and occasionally revising those which appeared in the first two volumes of the revision. Information first appearing in the present volume is distinguished by a bullet and revisions of previous addenda by a second bullet so that users of STC may more easily annotate their copies of the first two volumes.