1. J. Tauc, ?Amorphous and Liquid Semiconductors? (Plenum Press, London, 1974) p. 159.
2. J. Tauc, R. Grigorovici andA. Vancu,Phys. Status Solidi 15 (1966) 627.
3. E. A. Davis andN. F. Mott,Phil. Mag. 22 (1970) 903.
4. N. F. Mott andE. A. Davis, ?Electronic Processes In Non-crystalline Materials? (Clarendon Press, Oxford, 1979) pp. 291, 497.
5. G. R. Moridi andC. A. Hogarth, Proceedings 7th International Conference on Amorphous and Liquid Semiconductors (Edinburgh) (1977) edited by W. E. Spear (Centre for Industrial Consultancy, Edinburgh) p. 688.