Art , Photo
Art , PhotoPhotographic Determination of Stellar Parallaxes with the 60-inch Reflector
Free Download
Art , PhotoPhotographic Magnitudes of Stars in the Selected Areas of Kapteyn (1917)(en)(4s)
Free Download
- Art , Photo
Preliminary Note on the Distribution of Stars With Respect to the Galactic Plane (1917)(en)(6s)
Free Download 
Art , PhotoRelation of Color to Intrinsic Luminosity in Stars of the Same Spectral Type (1919)(en)(7s)
Free Download
