[451] Payne, H. C. 263, 1924.

[452] Preface, Henry Draper Catalogue.

[453] M. N. R. A. S., 83, 403, 1923.

[454] H. C. 258, 1924.

[455] Chapter IV, [p. 52].

[456] Shapley, H. B. 805, 1924.

[457] Shapley, Rep. Spectr. Class. Com., I. A. U., 1925.

[458] See [Appendix].

[459] Mt. W. Contr. 244, 1922; 262, 1923.

[460] H. C. 264, 1924; cf. Lindblad, Ap. J., 59, 305, 1924.