Biographisches Lexikon der hervorragenden Ärzte aller Zeiten und Völker. Edited by August Hirsch, with the assistance of Ernest Gurlt and A. Wernich. 6 vols.

This is one of the best sources of medical biography up to 1880, with useful bibliographical notes. Articles were written by many physicians, whose names were mentioned on the title page. Gurlt and Wernich assisted Hirsch in the massive editorial process. Digital facsimile of all the volumes from Google Books at this link. A revised edition, incorporating a revision of No. 6720, was completed in 1935 and reprinted, Munich, 1962. See also No.6732.