First Day Cover with printed cachet and stamp. Cachet depicts the Atomium monument from the 1958 World's Fair Exhibition in Brussel's Belgium. Designed by engineer André Waterkeyn (1917-2005) and architects André…
First day cover created by Artmaster includes cachet depicting a 3D image of a nonexistent molecule. Stamp depicts chemical glassware. Envelope is signed by Herman S. Bloch, the inventor of the catalytic converter.