Scott Catalog # : 4224 - 4227 / Fleetwood First Day Covers.
Set includes: 4224 Gerty Cori / 4225 Linus Pauling / 4226 Edwin Hubble and 4227 John Bardeen.
Have description of the stamp subject...
Scott Catalog # : UX445 - UX448 Miami, FL Postmark / Fleetwood Postal Cards First Day Covers.
Each has Pre-Printed 23¢ Postage and measure 4 1/4" x 6".
Image shows both front and back of...