1. R. W. G. Wyckoff, Crystal Structures, Vol. 3, Interscience, New York (1965).
2. I. N. Kurkin, Paramagnetic Resonance [in Russian], No. 5, Kazan' (1969), p. 31.
3. A. I. Smirnov, Abstract of Candidate's Thesis, Moscow State University, Moscow (1968).
4. M. I. Samoilovich, Abstract of Candidate's Thesis, Institute of Crystallography, Academy of Sciences of the USSR, Moscow (1967).
5. M. L. Meil'man, Abstract of Candidate's Thesis, Kazan' State University, Kazan' (1969).