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Now showing items 1-5 of 5
Ten Mathematical Equations 6
(1971)
First-day cover with five stamps from The Ten Mathematical Equations that Changed the Face of the Earth series. Issued by Nicaragua on May 15, 1971.
Ten Mathematical Equations 7
(1971)
First-day cover with five stamps from The Ten Mathematical Equations that Changed the Face of the Earth series. Issued by Nicaragua on May 15, 1971.
Donation of Blood and Blood Transfusion 12
(1965-09-01)
One stamp and first day cover.
Radiology 6
(1954)
One stamp, one-first day cover, and one cut square.
Radiology 5
(1963)
Two first-day covers.