United States #3906-09 - 37¢ American Scientists - 4 Varieties, Attached Self-Adhesive Plate Block
Varieties include:
- #3906 - Barbara McClintock
- #3907 - Josiah Willard Gibbs
- #3908 - John von Neuman
- #3909 - Richard Feynman
*Plate number and position may vary from image shown.