1. A general survey was presented in “Electronic Materials”, ed. by N. B. Hannay and U. Colombo (Plenum, New York 1973)
2. For a review of alternate analytic methods, see “Modern Physical Techniques in Materials Technology”, ed. by T. Mulvey and R. K. Webster (Oxford University Press, 1974) and the collection of articles in Rey. Phys.11, 1 (1976)
3. J. I. Pankove:Optical Processes in Semiconductors (Prentice-Hall, Englewood Cliffs N.J., 1971)
4. J. C. Phillips:Bonds and Bands in Semiconductors (Academic Press, New York 1973)
5. Raman scattering related to impurities was first proposed by R. J. Elliot and R. Loudon: Phys. Lett.3, 189 (1963). Experiments on GaP by C. H. Henry, J. J. Hopfield, L. C. Luther: Phys. Rev. Lett.17, 1178 (1966). A recent reference is J. Doehler: Phys. Rev. B12, 2917 (1975)