1. A. K. Ivanov-Shits and I. V. Murin, Solid State Ionics (Izd-vo SPb Gos. Univ., St. Petersburg, 2000), Vol. 1 [in Russian].
2. B. Monnaye, C. Garrault, G. Perez, and R. Bouaziz, Compt. Rend., Ser. C, Sci. Chim. 278, 251 (1974).
3. B. Monnaye, Rev. Chim. Miner. 13, 422 (1976).
4. H. Y. P. Hong, Mater. Res. Bull. 13, 117 (1978).
5. E. Plattner and H. Voellenkle, Monatsh. Chem. Verwandte Teile Wissensch. 110, 693 (1979).