[19] C. Wolf, Bulletin Astronomique, tom. i., p. 596.
[20] American Journal of Science, vol. xxxviii., p. 3.
[21] G. H. Darwin, Nature, vol. xxxi., p. 506.
[22] Proceedings of the American Philosophical Society, vol. xxii., p. 109.
[23] De Vries, Die Mutationstheorie, Bd. II., p. 714.
[24] Formation Mécanique du Système du Monde. See also Le Problème Solaire, by the Abbé Th. Moreux, p. 63 et seq.
[25] Revue des Questions Scientifiques, January, 1904.
[26] The Earth's Beginnings, p. 247.
[27] Astrophysical Journal, vol. xi., p. 130.