1
2
Έκδοση: 1951
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 38
3
Έκδοση: 1937
Superior document: Annals of the Astronomical Observatory of Harvard College 89,10
4
5
6
Έκδοση: 1945
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series I 273
7
Έκδοση: 1945
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series I 274
8
9
Έκδοση: 1950
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 35
10
Έκδοση: 1946
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series I 282
11
Έκδοση: 1953
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 47
12
Έκδοση: 1960
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 161
13
Έκδοση: 1954
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 67
14
Έκδοση: 1957
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 108
15
Έκδοση: 1956
Superior document: Reprints / The Astronomical Observatory of Harvard College : Series II 80