1. T. F. Fedorov and Yu. B. Kuz'ma, Neorgan. Materialy,3, 1498 (1967).
2. K. I. Portnoi, Yu. V. Levinskii, et al., Metally,2, No. 4, 171 (1967).
3. R. Kieffer and F. Benesovksy, Hartstoffe, Vienna (1963).
4. Yu. V. Voroshilov and Yu. B. Kuz'ma, Izv. Vysshikh Uchebn. Zavedenii, Tsvetn. Met., No. 4, 147 (1967).
5. Yu. B. Kuz'ma and M. V. Chepiga, Neorgan. Materialy,5, 49 (1969).