Alexander E. Outerbridge, Jr., A Fourth State of Matter. Lecture delivered before the Franklin Institute, 17 February 1881. Journal of the Franklin Institute of the State of Pennsylvania, Volume 81. By Franklin Institute (Philadelphia, Pa.). Page 287+
La diferencia entre un "tubo de Crookes" y un "tubo de Geissler" es que: En un tubo de Geissler la exhaustión es mucho menor que en un tubo de Crookes, la luz en el tubo Geissler es producto de la luminiscencia del gas residual. (Transactions, Volume 9. Hertfordshire Natural History Society and Field Club. The Club, 1898. Page 136.)
Radio-activity induced by the oscillatory discharge, or, The subsequent radio-active emanation from substances exposed to the Tesla oscillatory discharge. Harry Marshall Diemer, Ralph Stuart Cooper. Cornell University, 1903. Page 43+.
William Crookes, On Radiant Matter. Lecture delivered before the British Association for the Advancement of Science, at Sheffield, Friday, 22 August 1879. The Popular Science Monthly, Volume 16. D. Appleton, 1880. Pg157+
britannica.com
global.britannica.com
Encyclopaedia Britannica. «Sir William Crookes»(en inglés). Consultado el 5 de noviembre de 2015.