1. H. Schulman, W. D. Compton, Color Centers in Solids, R. Smoluchowski& N. Kurti eds., Pergamon Press, Oxford, 1963.
2. W. B. Fowler, Physics of Color Centers, W. B. Fowler ed., Academic Press, New York and London, 1968.
3. C. Ortiz, C. N. Afonso, P. Pokrowsky and G. C. Bjorklund, Appl. Phys. Lett. 43(12), 1102 (1983).
4. R. M. Montereali, G. Baldacchini, L. C. Scavarda do Carmo, Thin Solid Films 201, 106 (1991).
5. G. Baldacchini, M. Cremona, R. M. Montereali, L. C. Scavarda do Carmo, in Defects in Insulating Materials, O. Kanert and J. M. Spaeth eds., World Scientific, Singapore, 1993, p. 176.