In 1886, Joseph Sabin began work on the "Biblioteca Americana, The Dictionary of Books Relating to America," which has been for years the most complete guide to literature and research materials about American culture. Unfortunatly, in the 19th-century travel was difficult, photo-copying unavailable, and descriptive cataloging unhelpful. As a result, Sabin and his successors were unable to examine or, in some cases, learn much about the materials that they describe. Furthermore, there is no subject or title index, nor is there an index of joint authors in the origional work. Thompson has added these indexes, as well as materials that Sabin overlooked, including Mexicana and Canadiana, or of which he was unaware. In addition, he has updated each entry using the descriptive portion of its Library of Congress card.