1. L. I. Anatychuk, Thermoelements and Thermoelectric Devices: A Handbook (Naukova Dumka, Kiev, 1979) [in Russian].
2. L. D. Ivanova, M. A. Korzhuev, L. I. Petrova, et al., Proceedings of an International Workshop, St. Petersburg, 2004, p. 422 [in Russian].
3. Physical Properties of Rare-Earth Chalcogenides, Ed. by V. P. Zhuze (Nauka, Leningrad, 1973) [in Russian].
4. S. A. Langston and B. Lewis, J. Rhys. Chem. Sol. 24, 1387 (1963).
5. V. G. Kuznetsov and K. K. Palkina, Zh. Neorg. Khim. 8, 931 (1963).