United States #3906-09 - 37¢ American ScientistsSelf-Adhesive Mint Block of 4
Varieties include:
- #3906 - Barbara McClintock
- #3907 - Josiah Willard Gibbs
- #3908 - John von Neuman
- #3909 - Richard Feynman
Mint condition, never hinged.
*Stamp positions may vary.