by F.H. Seares, J.C. Kapteyn and P.J. van Rhijn ; assisted by Mary C. Joyner and Myrtle L. Richmond

Carnegie Institution of Washington 1930 Carnegie Institution of Washington publication no. 402 , Papers of the Mount Wilson Observatory v. 4

Available at 4 libraries

by J.C. Kapteyn

Publisched by the Astronomical Laboratory at Groningen , Hoitsema 1911

Available at 1 libraries

by J.C. Kapteyn

Published by the Astronomical Laboratory at Groningen , Hoitsema 1906

Available at 2 libraries

by J.C. Kapteyn

P. Noordhoff [1903]-1916

[1st paper] , 2nd paper

Available at 6 libraries

par J.C. Kapteyn et W. Kapteyn

J. Müller 1885

Available at 1 libraries