1
2
Published: 1934
Superior document: Publications of the Observatory of the University of Michigan 6,5
3
Published: 1923
Superior document: Publications of the Astronomical Observatory of the University of Michigan 3,[14]
4
Published: 1932
Superior document: Publications of the Observatory of the University of Michigan 4,7
5
6
Published: 1932
Superior document: Publications of the Observatory of the University of Michigan 4,11
7
Published: 1923
Superior document: Publications of the Astronomical Observatory of the University of Michigan 3,[15]