1. Avramov, I., Pascova, R., Samouneva, B., Gutzow, I.: Phys. Chem. Glass. 20, 91 (1979)
2. Avramov, I., Grantcharova, E., Gutzow, I.: J. Non Cryst. Solids 52, 111 (1981)
3. Avramov, I., Grantcharova, E., Gutzow, I.: J. Non Cryst. Solids 91, 386 (1987)
4. Avramov, I., Grantcharova, E., Gutzow, I.: J. Cryst. Growth 87, 305 (1988)
5. Bertocci, U.: Surf. Sci. 15, 286 (1969)