1. Venevtsev, Yu.N., Gagulin, V.V., and Lyubimov, V.N., Segnetomagnetiki (Magnetoelectrics), Moscow: Nauka, 1982, p. 161.
2. Sosnowska, I., Przenioslo, R., Fischer, P., and Murashov, V.A., J. Magn. Magn. Mater., 1996, vol. 160, p. 383.
3. Zalessky, A.V., Frolov, A.A., Khimich, T.A., et al., Europhys. Lett., 2000, vol. 50, p. 547.
4. Zvezdin, A.K. and Pyatakov, A.P., Usp. Fiz. Nauk, 2004, vol. 174, p. 465.
5. Pokatilov, V.S., Pokatilov, V.V., and Sigov, A.S., Fiz. Tverd. Tela, 2009, vol. 51, no. 3, p. 58.