1. Piacente, V. and Matousek, J. Silikaty, 4, 264 (1973).
2. Hastie, J. W., Horton, W. S., Plante, E. R., and Bonnell, D. W. High Temp. Sci, 14, 669 (1982).
3. Hastie, J. W. and Bonnell, D. W. High Temp. Sci., 19, 275 (1985).
4. Dhima, A., Stafa, B., and Allibert, M. High Temp. Sci., 21, 143 (1986).
5. Stafa, B. These prüsenteü ü l’institut National polytechnique de Grenoble, 1983.