1. V. A. Obolonchik and G. V. Lashkarev, Selenides and Tellurides of Rare-Earth Metals and Actinides [in Russian], Naukova Dumka, Kiev (1966).
2. V. A. Obolonchik and G. V. Lashkarev, in: Problems in Rare-Earth Metals Theory and Application [in Russian], Nauka, Moscow (1964), p. 166.
3. V. P. Zhuze, A. V. Golubkov, E. V. Goncharova, and V. M. Sergeeva, Fiz. Tverd. Tela, 6: 257 (1964).
4. V. P. Zhuze, A. V. Golubkov, E. V. Goncharova, T. I. Komarova, and V. M. Sergeeva, Fiz. Tverd. Tela, 6: 268 (1964).
5. V. E. Adamyan, A. V. Golubkov, and G. M. Loginov, Fiz. Tverd. Tela, 7: 301 (1965).