1. M. Ataka and M. Asai, J. Cryst. Growth 90, 86 (1988).
2. A. A. Chernov, Phys. Rep. 288, 61 (1997).
3. V. V. Voronkov, Kristallografiya 18, 32 (1973) [Sov. Phys. Crystallogr. 18, 19 (1973)].
4. V. V. Voronkov, in Crystals: Growth, Properties and Applications, Ed. by A. A. Chernov and H. Muller-Krumbhaar (Springer-Verlag, Berlin, 1983), Vol. 9, p. 74.
5. V. V. Voronkov, Kristallografiya 15(1), 135 (1970) [Sov. Phys. Crystallogr. 15, 108 (1970)].