1. É. L. Nagaev, Usp. Fiz. Nauk 166, 833 (1996).
2. J. Goodenough, Magnetism and the Chemical Bond (Interscience, New York, 1963) [Russian original, Metallurgiya, Moscow, 1968].
3. H. H. Heikens, G. A. Wiegers, and C. F. van Bruggen, Solid State Commun. 24, 205 (1977).
4. G. V. Loseva, S. G. Ovchinnikov, and L. I. Ryabinkina, Fiz. Tverd. Tela (Leningrad) 28, 2048 (1986) [Sov. Phys. Solid State 28, 1145 (1986)].
5. L. P. Gor’kov, Usp. Fiz. Nauk 168, 665 (1998).