1. N. Nagoka, J. Coll. of Sci., Tokyo Univ.,2, 283 (1888).
2. R. S. Carmichael and M. D. Fuller, J. Geomag. and Geol.,3, 181 (1967).
3. A. A. Rodionov and É. I. Gordienok, Izv. VUZ, Fizika, No. 1, 52 (1973).
4. R. Bosorth, Ferromagnetism [Russian translation], IL (1956).
5. A. G. Zvegintsev, V. A. Poponnikova, and A. A. Rodionov, Materials of a Jubilee Conference of Siberia and the Far East [in Russian], Krasnoyarsk, 1969 (in press).