Obreja, P., F. Comanescu, M. Purica, R. Gavrila, and D. Cristea. “Polymers Doped With Metal Oxide Nanoparticles With Controlled Refractive Index”. Polimery, vol. 52, no. 9, Aug. 2022, pp. 679-85, http://ichp.vot.pl/index.php/p/article/view/1462.