Wheaton, Bruce R. (1978). "Philipp Lenard and the Photoelectric Effect, 1889-1911". Historical Studies in the Physical Sciences. 9: 299–322. doi:10.2307/27757381. JSTOR27757381.
de Broglie, Louis Victor. "On the Theory of Quanta"(PDF). Foundation of Louis de Broglie (English translation by A.F. Kracklauer, 2004. ed.). Retrieved 25 February 2023.
Wheaton, Bruce R. (1978). "Philipp Lenard and the Photoelectric Effect, 1889-1911". Historical Studies in the Physical Sciences. 9: 299–322. doi:10.2307/27757381. JSTOR27757381.