1. Akbaeva, G.M., Dantsiger, A.Ya., and Razumovskaya, O.N., in Proc. Int. Conf. “Electroceramics IV,” Aachen, 1994, vol. 1, p.535.
2. Smolenskii, G.A., Fizika segnetoelektricheskikh yavlenii (The Physics of Ferroelectric Phenomena), Leningrad: Nauka, 1985.
3. Milov, E.V., Akbaeva, G.M., Gavrilyachenko, V.G., and Semenchev, A.F., Phys. Solid State, 2012, vol. 54, no. 5, p.932.
4. Truell, R., Elbaum, C., and Chick, B.B., Ultrasonic Methods in Solid State Physics, Academic, 1969.
5. Nozdrev, V.F. and Fedorishchenko, N.V., Molekulyarnaya akustika (Molecular Acoustics), Moscow: Vysshaya Shkola, 1974.