1. See, e.g., K. Seeger: Semiconductor Physics, 5th edn., Springer Ser. Solid-State Sci., Vol. 40 ( Springer, Berlin, Heidelberg 1991 )
2. R. Dingle: Proc. 13th Int’l Conf on Physics of Semiconductors, ed. by F.G. Fumi ( North-Holland, Amsterdam 1976 )
3. A. Yariv: Quantum Electronics 3rd edn. (Wiley York, New York 1988) pp. 267-.268
4. A. Yariv: Quantum Electronics, 3rd edn. ( Wiley York, New York 1988 ) p. 270
5. A. Yariv: Quantum Electronics, 3rd edn. ( Wiley York, New York 1988 ) p. 272