Ragin, Tomasz, Jacek Mariusz Zmojda, Marcin Kochanowicz, and Dominik Dorosz. “Spectroscopic Properties of Heavy Metal Oxide Glasses Doped With Er3+ Ions for Mid-Infrared Applications”. Photonics Letters of Poland 7, no. 2 (July 1, 2015): pp. 38–40. Accessed May 28, 2024. https://photonics.pl/PLP/index.php/letters/article/view/7-14.