1. B. Jaffe, W. R. Cook, and H. Jaffe, Piezoelectric Ceramics (Academic, New York, 1971; Mir, Moscow, 1974).
2. V. A. Isupov, in Ferroelectrics and Related Materials, Ed. by G. A. Smolenskii (Gordon and Breach, New York, 1983); V. A. Isupov, in The Physics of Ferroelectric Phenomena (Nauka, Leningrad, 1985), Chap. 15.
3. V. A. Freimanis, Ya. Ya. Kruchan, et al., Neorg. Mater. 16(6), 1044 (1980).
4. K. Kakegawa, J. Mohri, T. Takahashi, et al., Solid State Commun. 24(11), 769 (1977).
5. Y. Abe, K. Kakegawa, and Y. Sasaki, Solid State Commun. 72(11), 1071 (1989).