Taylor, William B. (1877). "Kinetic theories of gravitation". Annual report of the Board of Regents of the Smithsonian Institution. Washington: Government Printing Office. ss. 270-271. Erişim tarihi: 4 Ocak 2020.
DeKosky, Robert K. (1973). "Spectroscopy and the Elements in the Late Nineteenth Century: The Work of Sir William Crookes". The British Journal for the History of Science. 6 (4): 400-423. doi:10.1017/S0007087400012553.