1. T. S. Al’tshuler and M. S. Bresler, Zh. Éksp. Teor. Fiz. 115, 1860 (1999) [JETP 88, 1019 (1999)].
2. T. S. Al’tshuler, M. S. Bresler, Yu. V. Goryunov, et al., Fiz. Tverd. Tela (St. Petersburg) 44, 1469 (2002) [Phys. Solid State 44, 1536 (2002)].
3. M. Kasaya, H. Kimura, Y. Isikawa, et al., in Valence Fluctuations in Solids, Ed. by L. M. Falicov, W. Hanke, and M. B. Maple (North-Holland, Amsterdam, 1981), p. 251.
4. T. S. Al’tshuler, M. M. Zaripov, and V. N. Mironov, in Abstracts of VII All-Union Symposium on Spectroscopy of Crystals Activated by Ions of Rare-Earth and Transition Metals (Leningrad, 1982), p. 11.
5. C. M. Jackson, K. Y. M. Wong, M. Hardiman, et al., Bull. Am. Phys. Soc. 28, 270 (1983).