1. A. G. Gurevich and G. A. Melkov, Magnetic Oscillations and Waves [in Russian], Fizmatlit, Moscow (1994).
2. C. Kittel, Рhys. Rev., 73, No. 2, 155 (1948).
3. J. R. Macdonald, Proc. Phys. Soc., 64, Pt. 11, No. 383A, 968 (1951).
4. J. Smit and H. J. Beljers, Philips Res. Rep., 10, No. 2, 113 (1955).
5. H. Suhl, Phys. Rev., 97, No. 2, 555 (1955).