Some Remarks on the Contraction of Groups
A statistical study of pulsating stars.second paper: The irregular variable A.R. Her
Some results of a spectroscopic study of the atmosphere of 31 Cygni
A statistical study of pulsating stars.Seventh paper: The variables in M 2
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. Fourteenth paper: Irregular variables in & Cen