1. N. I. Leonyuk, Kristallografiya, 53, No. 2, 349 (2008).
2. O. K. Kuvandikov, Kh. O. Sharkov, Z. Shodiev, et al., Book of Abstracts. “Moscow International Symposium on Magnetism”, Moscow (2005), p. 258.
3. E. A, Popova N. I. Leonyuk, M. N. Popova, et al., Phys. Rev., 76 B, 1 (2007).
4. A. D. Mills, Inorgan. Chem., 1, 960 (1962).
5. W. A. Dollase and R. J. Reeder, Am. Mineral., 71, 163 (1986).