[270] Payne, H. C. 263, 1924.
[271] Hopfield, Nature, 112, 437, 1923.
[272] Proc. Roy. Soc., 80A, 50, 1907.
[273] H. C. 256, 1924.
[274] M. N. R. A. S., 84, 499, 1924.
[275] Fowler, Report on Series in Line Spectra, 1922.
[276] Curtis and Burns, unpub.
[277] Personal letter.
[278] Russell and Saunders, Ap. J., 61, 38, 1925.
[279] Menzel, H. C. 258, 1924.