2022-03-082022-03-081971https://hdl.handle.net/2152.3/11376"Einstein's Law" 20c. stamp depicting a "mushroom cloud, signifying an atomic explosion." "Tsiolkovsky's Law" 1cor. stamp depicting an Apollo spacecraft and Saturn rocket.Two stamps from The Ten Mathematical Equations that Changed the Face of the Earth series. Issued by Nicaragua on May 15, 1971.Stamp collectingPostage-stamp albumsNicaraguaEinstein, Albert, 1879-1955Nuclear explosionsNuclear fissionT︠S︡iolkovskiĭ, K. (Konstantin), 1857-1935Apollo (Spacecraft)