1. D. Trandafir, M. Vasilescu, S. Simon, J. Sol-Gel Sci. Technol. 63, 425–434 (2012)
2. C.J. Brinker, G.W. Scherer, Sol-Gel Science (Academic Press, New York, 1990)
3. J. Wong, C. Angel, Glass structure by spectroscopy (Marcel Dekker, Basel, 1976)
4. D.L. Griscom, Glass Sci. Technol., vol. 4B. (Academic Press, Boston, 1990)
5. H. Tominaga, Y. Ono, T. Keii, J. Catal. 40, 197–202 (1975)