[200] A. Fowler, M. N. R. A. S., 70, 176 and 484, 1909.

[201] C. R., 177, 1205, 1923.

[202] Pluvinel and Baldet, Ap. J., 34, 89, 1911.

[203] M. N. R. A. S., 76, 640, 1916.

[204] Chapter XIV, [p. 167].

[205] Fowler, Report on Series in Line Spectra, 164, 1922.

[206] Smyth, Proc. Roy. Soc., 103A, 121, 1923.

[207] Vegard, Videns. Skr., 1, nos. 8, 9, 10, 1923, where previous work is summarized.

[208] Vegard, Proc. Amst. Ac., 27, 1 and 2, 1924.

[209] A. Fowler, M. N. R. A. S., 70, 484, 1909.