Grolier encyclopedia of knowledge volume 20: Wor-Zyg-Index/ - Danbury, Connecticut: Grolier Incorporated, 1991. - 416 pages: colored images; 24 cm. Includes Index. ISBN: 0717253007 0717253201 Subjects--Topical Terms: Encyclopedias and dictionaries. Dewey Class. No.: 031 / G894