1. Zhili, C., Xi, Y., Cross, L.E.: Ferroelectrics 49 (1983) 213.
2. Deb, K.K.: Ferroelectrics 82 (1988) 45.
3. Chechkin, V.V., Savenkov, G.E., Didkovskaya, O.S., Venevtsev, Yu., Klimov, V.V.: Inorg. Mater. 16 (1980) 1111.
4. Remeika, J.P., Glass, A.M.: Mater. Res. Bull. 5 (1970) 37.
5. Shiosaki, T., Lian, J., Adachi, M., Kawabata, A.: Ferroelectrics 92 (1989) 23.