1. W. D. Kingery, H. K. Bowen and D. R. Uhlmann, ?Introduction to Ceramics? (John Wiley and Sons, New York, London, Sydney and Toronto, 1976) p. 42.
2. D. L. Branson, J. Amer. Ceram. Soc. 48 (1965) 591.
3. C. Leblud, M. R. Anseau, E. Di Rupo, F. Cambier and P. Fierens, J. Mater. Sci. 16 (1981) 4716.
4. G. Valensi, Compt. Rend. 202 (1936) 309.
5. L. Margrave, ?The Characterization of high temperature vapours? (John Wiley and Sons, New York, London, Sydney and Toronto, 1967) p. 497.