3 Stamps of topic "Mathematics"

All 3 stamps of the topic "Mathematics" of the Deutschen Bundespost (german post BRD). The sort is in reverse chronological order, so the newest stamps are at the beginning.

Stamp: Friedrich Wilhelm Bessel Astronom Mathematiker
Friedrich Wilhelm Bessel Astronom Mathematiker
Stamp: Adam Riese (Mathematiker, Rechenmeister)
Adam Riese (Mathematiker, Rechenmeister)
Stamp: Leonhard Euler (Mathematiker)
Leonhard Euler (Mathematiker)