A statistical study of pulsating stars.Fourth paper: The variables in Messier 3
A statistical study of pulsating stars.Fifth paper: The variables stars in M 53 and N.G.C. 3201
A statistical study of pulsating stars.Sixth paper: Variables in miscellaneous clusters
Note On a Generalization of Schwarz' Lemma
Some results of a spectroscopic study of the atmosphere of 31 Cygni