1. S.A. Solin: Physica 99B, 443 (1980)
2. S.A. Solin and N. Caswell: J. Raman Spectroscopy 10, 129 (1981)
3. M.S. Dresselhaus and G. Dresselhaus: Adv. Phys. 30, 139 (1981); Topics in Applied Physics, Vol. 51, “Light Scattering in Solids III”, eds. M. Cardona and G. Guntherodt, ( Springer, Berlin, 1982 )
4. B.J.C. Van der Hoeven and P.H. Keesom: Phys. Rev. 130, 1318 (1963)
5. R.W. Lynch and H.G. Drickamer: J. Chem. Phys. 44, 181 (1966)