1. R. FOSTER, ?Organic Charge Transfer Complexes? (Academic Press, London, 1960).
2. J. MORT and D. M. PAI, Photoconductivity and Related Phenomena (Oxford, New York, 1976).
3. H. J. HOVEL, ?Semiconductors and Semi-metals? Vol. 11 (Academic Press, New York, 1975) pp. 211?16.
4. ?Handbook of Chemistry and Physics? 57th edn (CRC Press, 1976?77) p. E-104.
5. ?Handbook of Chemistry and Physics? 57th edn (CRC Press, 1976?77) p. E-81.