Four items signed by important medical researchers, including two Nobel Prize winners. Includes: a glossy 5 x 7 head-and-shoulders photo of geneticist Edward L. Tatum, who shared the 1958 Nobel Prize in Physiology or Medicine for showing that genes control individual steps in metabolism, signed in fountain pen; a glossy 8 x 10 photo of geneticist Howard M. Temin, who shared the 1975 Nobel Prize in Physiology or Medicine for his discovery of reverse transcriptase, signed in black felt tip; and a booklet entitled "Discovering Tetracycline" and a glossy 7 x 5 photo of Lloyd H. Conover, inventor of the antibiotic tetracycline, both signed in black ballpoint by Conover (with the photo inscribed). In overall fine condition. Accompanied by an unsigned photo of Tatum.