1. Born, M., andK. Huang: Dynamical Theory of Crystal Lattices. Oxford: Clarendon Press, p. 129 (1956).
2. Kleinman, L.: Phys. Rev.128, 2614 (1962).
3. Segmüller, A.: Physics Letters4, 277 (1963).
4. Göttlicher, S., andE. Wölfel: Z. Elektrochem.63, 891 (1959).
5. James, R. W.: The Optical Principles of the Diffraction of X-rays. London: G. Bell and Sons, p. 50 (1958); International Tables for X-ray Crystallography. The Kynoch Press, Birmingham, Vol. II, p. 314 (1959).