Tichá, H., Schwarz, J., Tichý, L., Mertens, R. Physical properties of PbO-ZnO-P2O5 glasses II. refractive index and optical properties. Journal of Optoelectronics and Advanced Materials. 2004, 6(3), 747-753. ISSN 1454-4164. E-ISSN 1841-7132.