This guide offers a systematic approach to the wide variety of published biographical information on men and women of science in the life, earth and physical sciences, primarily from 1989 to 2006, and complements Library of Congress Science Tracer Bullet "TB88-3" ("Biographical Sources in the Sciences," compiled 1988 [ED306074]) and "TB06-7" ("Biographical Sources in the Sciences--General Works and National Sources," compiled 2006). Works previously listed in "TB88-3" have not been retained, but older works which did not make it into the previous bibliography have been included. Both historical and contemporary scientists are covered, with emphasis on Americans. As in "TB88-3," bibliographic citations include the indication of illustrations, particularly portraits, and the inclusion of preliminary pagination extending to more than 13 pages and unnumbered as well as numbered series notes. Departing from the usual Library of Congress Science Tracer Bullet format, where one subject is treated per publication, "Biographical Resources in the Sciences" instead is being issued in three parts, "General Works and National Sources; Life, Earth and Physical Sciences (1989-2006)"; and "Technology and Computer Sciences (1989-2006)." Each Tracer Bullet contains an introduction to the topic that includes basic works on biography and a general listing of subject headings. This part, "TB06-4" includes Agriculture, Veterinary Medicine, Conservation; Astronomy; Biological Sciences; Chemistry; Geology, Mineralogy, Paleontology; Mathematics; Medical Sciences; Physics; Abstracting and Indexing Services; Journals; and Selected Internet Resources.