The purchase of this stamp/s will earn you 8 points valued at $0.16.
Mint and never hinged.
#4224 41¢ American Scientists: Biochemist Gerty Cori (1896-1957), together with her husband Carl, they made discoveries that later became the basis for our knowledge of how cells use food and convert it into energy.
#4225 41¢ American Scientists: Structural chemist Linus Pauling (1901-1994) determined the nature of the chemical bond linking atoms into molecules.
#4226 41¢ American Scientists: Astronomer Edwin Hubble (1889-1953) played a large role in explaining the nature of the universe.
#4227 41¢ American Scientists: Theoretical physicist John Bardeen (1908-1991) co-invented the transistor.
#4227a Horizontal strip of four, #4224-4227