1. Klein, M.V.: Light Scattering in Solids, Topics in Applied Physics Vol. 8, Cardona, M. (ed.), Berlin: Springer, 1975.
2. Dean, P.J.: Prog. Cryst. Growth Charact. 5 (1982) 89.
3. Kisker, D.W., Tews, H., Rehm, W.: J. Appl. Phys. 54 (1983) 1332.
4. Reynolds, D.C., Bajaj, K.K., Litton, C.W.: Phys. Rev. B 32 (1985) 8242.