1
Published: 1948
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 22
2
Published: 1950
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 34
3
Published: 1956
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 84
4
Published: 1955
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 70
5
Published: 1961