Signed First Day Cover.
This Canadian-American chemist-inventor and author is credited with a wide range of inventions; he held 58 U.S. patents and 450 foreign patents, among them a microcrystalline cellulose for pharmaceutical use and a microcrystalline collagen. Signed First Day Cover, 6½" X 3½", cancelled in Cincinnati, Ohio on November 10, 1972 with..... More