1. Yu. F. Kargin, V. I. Burkov, A. A. Mar’in, and A. V. Egoryshev, Sillenite Crystals: Synthesis, Structure, Properties (Institute of General and Inorganic Chemistry, Moscow, 2004) [in Russian].
2. A. A. Ballman, J. Cryst. Growth 1, 37 (1967).
3. A. I. Safonov, S. A. Baryshev, T. I. Nikiforova, et. al., Sov. Phys. Crystallogr. 13(5), 797 (1968).
4. A. T. Sobolev, Yu. L. Kortlov, and V. B. Kravchenko, Sov. Phys. Crystallogr. 23(1), 93 (1978).
5. Yu. S. Kuz’minov, M. G. Livshits, and V. D. Sal’nikov, Sov. Phys. Crystallogr. 14(3), 297 (1969).