1. P.P. Budnikov, A.M. Ginstling, Principles of Solid state Chemistry, /Ed. Kenneth Shaw, Maclaren and Sons Ltd./, London, 1968, p. 155.
2. A.K. Galwey, Chemistry of Solids, Chapman and Hall Ltd., London, 1967, p. 163.
3. E. Hoffmann, S. Patai,J. Am. Chem. Soc., 72 /1950/ 5098.
4. E. Hoffmann, S. Patai,J. Chem. Soc., /1955/ 1797.
5. P.P. Budnikov, A.M. Ginstling, Principles of Solid State Chemistry, /Ed. Kenneth Shaw, Maclaren and Sons Ltd./, London, 1968, p. 156.