1. E. Holland-Moritz and G. H. Lander, in Handbook of the Physics and Chemistry of Rare Earths, Vol. 19 (1994), Ch. 130.
2. M. Loewenhaupt and K. H. Fisher, in Handbook of the Physics and Chemistry of Rare Earths, Vol. 16 (1993), Ch. 105.
3. P. A. Alekseev, W. Bührer, V. N. Lazukov, E. V. Nefeodova, I. P. Sadikov, O. D. Chistyakov, and M. Zolliker, Physica B 217, 241 (1996).
4. V. N. Lazukov, P. A. Alekseev, E. S. Klement’ev, et al., Zh. Éksp. Teor. Fiz. 113, 1731 (1998) [JETP 86, 943 (1998)].
5. I. Felner, Solid State Commun. 56, 315 (1985).