1. M. E. Lines and A. M. Glass, Principles and Application of Ferroelectric and Related Materials (Clarendon, Oxford, 1977).
2. R. Poprawski, S. Matyjasik, and Yu. Shaldin, Phys. Status Solidi A 90, 107 (1985).
3. A. V. Dobrynin, N. P. Kazakov, and G. A. Gaida, Zarubezh. Elektron. Tekhn. 3 (1989).
4. N. Gavrilova, E. Maksimov, V. Novik, and S. Drozhdin, Sov. Phys. Solid State 27, 1559 (1985).
5. O. V. Avdeev, I. S. Barash, Yu. A. Vodakov, E. N. Mo- khov, S. S. Nagalyuk, A. D. Roenkov, A. S. Segal’, T. Yu. Chemekova, and Yu. N. Makarov, in Proceedings of the 13th NKRK Conference (IKRAN, Moscow, 2008), p. 7.