1. B. Jaffe, W. R. Cook, Jr andH. Jaffe, ?Piezoelectric Ceramics? (Academic Press, London, New York, 1971).
2. Y. H. Xu, ?Ferroelectric and Piezoelectric Materials? (in Chinese) (Scientific Publishing Co., Beijing, China, 1978).
3. H. Thomann,Ferroelectrics 4 (1972) 141.
4. Idem, Z, Angew. Phys. 20 (1966) 554.
5. M. Takahashi,Jap. J. Appl. Phys. 9 (1970) 1236.