1. F. A. Kröger, The Chemistry of Imperfect Crystals, ( North- Holland Publishing Company, Amsterdam, 1964 ), p. 880.
2. Ref. 1, pp. 879–908.
3. J. R. Macdonald, J. Appi. Phys. 34, 538 (1963).
4. N. Sinharay and B. Meitzer, Solid State Electronics 7, 125 (1964).
5. M. A. Lampert and P. Mark, Current Injection in Solids, ( Academic Press, New York, 1970 ).