Geodesic

Varallgemeinerung eines Satzes von Mobius
p. 1-11
Une Contribution a la Theorie Axiomatique des Treillis
p. 12-18
On the nth Powers of the Primitive Nth roots of Unity
p. 19-23
On some Mathematical Aspects of an Interplanetary flight (to Mars). Part II. Boundary Conditions
p. 24-53