1. C. R. A. Catlow, K. M. Diller, M. J. Norgett, J. Corish, B. M. C. Parker andP. W. M. Jacobs;Phys. Rev.,18, 2739 (1978).
2. R. T. Sanderson:J. Chem. Educ.,44, 516 (1967).
3. R. T. Sanderson:Chemical and Bond Energy, Vol.21, inPhysical Chemistry, edited byE. M. Loebl (Academic Press, Brooklin, N. Y., 1976).
4. A. R. West:Solid State Chemistry and its Applications (John Wiley & Sons, New York, N. Y., 1984).
5. K. Thörmer andF. Lüty:Phys. Status Solid B,90, 277 (1978).