1. A. I. Akhiezer, V. G. Bar’yakhtar, and S. V. Peletminskii, Spin Waves (Nauka, Moscow, 1967; North-Holland, Amsterdam, 1968).
2. V. I. Ozhogin and V. L. Preobrazhenskii, Usp. Fiz. Nauk 155, 593 (1988) [Sov. Phys. Usp. 31, 713 (1988)].
3. M. H. Seavey, Solid State Commun. 10, 219 (1972).
4. E. A. Turov and M. P. Petrov, Nuclear Magnetic Resonance in Ferro-and Antiferromagnets (Nauka, Moscow, 1969).
5. Kh. G. Bogdanova, V. A. Golenishchev-Kutuzov, M. I. Kurkin, et al., Zh. Éksp. Teor. Fiz. 112, 1830 (1997).