1. See, for example, K. Seeger: Semiconductor Physics-An Introduction, 3rd Ed., Springer Ser. Solids-State Sci. Vol. 40 (Springer, Berlin, Heidelberg 1985) pp. 10–11
2. R. Dingle: Proc. 13th Int. Conf. on Physics of Semiconductors, edited by F.G. Fumi (North-Holland, New York 1976)
3. A. Yariv: Quantum Electronics, 3rd Ed. (Wiley, New York 1988) pp. 267–268
4. Ibid p. 270
5. Ibid p. 272