Reisfeld, Renata, C. K. Jørgensen, A. Bornstein, and H. Berthou. “Photo-Electron Spectra of Germanium, Arsenic and Lead-Containing Sulphide Glasses Favouring Lanthanide Luminescence”. CHIMIA 30, no. 10 (October 31, 1976): 451. Accessed April 5, 2025. https://www.chimia.ch/chimia/article/view/1976_451.