1
Published: [1942]
Superior document: Annals of the astronomical observatory of Harvard College 109,6
2
Published: 1951
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 36
3
Published: 1948
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 25
4
Published: [1943]
Superior document: Annals of the astronomical observatory of Harvard College 109,11