1. Yu. I. Smolikov, Yu. F. Shepelev, and A. A. Levin, Zh. Neorg. Khim., 34, No. 10, 2451–2468 (1989).
2. A. E. Teplykh, A. N. Pirogov, A. Z. Menshikov, and G. V. Bazuev, Fiz. Tverd. Tela, 42, No. 12, 2175–2182 (2000).
3. V. M. Loktev and Yu. G. Pogorelov, Fiz. Nizk. Temper., 26, No. 3, 231–261 (2000).
4. Yu. A. Izyumov and Yu. N. Skryabin, Usp. Fiz. Nauk, 171, No. 2, 121–148 (2001).
5. S. F. Palguev, Zh. Prikl. Khim., 73, issue 11, 1745–1755 (2000).