Dr. Kler was an expert stamp collector of stamps with a medical theme. He was the author of the Minkus Publications’ Medicine on Stamps (1969) containing interesting accounts of medical history; for ten years, he was the author of yearly supplements. In 1970, the Home News called him the world’s leading medical stamp collector.” Dr. Kler was author of a feature article on medical stamps in Medical Times.
Dr. Kler’s extensive Medicine on Stamps collections consisted of over 16