[47] Wilsing and Scheiner, Pots. Pub., 24, No. 74, 1919.
[48] Pots. Pub., 24, No. 76, 1920.
[49] H. A., 76, 107, 1916.
[50] A.N., 193, 356, 1912.
[51] A. N., 218, 210, 1923; ibid., 219, 22 and 354, 1923; Die Strahlung der Sterne, Berlin, 1924.
[52] Rep., Smithsonian Ap. Obs., 1924.
[53] Pop. Ast., 21, 105, 1923.
[54] M. N. R. A. S., 85, 212, 1925.
[55] Pub. Dom. Ap. Obs., 2, 12, 1923.
[56] Ap. J., 55, 202, 1922.