[7] Β. S. Eawal, Ε. Κ. МаоСгопв; J. Non-Cryst. Solids, 1978, 28, 337.
[8] Β. M. Loeffler et al.; Proc. 6th Lunar. Soc. Conf., Pergamon, New York (1975), p. 2663.
[10] N. F. Mott, Ε. A. Davis; "Electronics Process in Non-Crystal-Line Solids, Oxford, London (1971).