1. W. Witthuhn and W. Engel, Electric Quadrupole Interaction in Noncubic Metals, in Topics in Current Physics Vol. 31, Hyperfine Interactions of Radioactive Nuclei, Ed. J. Christiansen, Springer Verlag, Berlin, Heidelberg 1983
2. R. Seeböck, Diplomarbeit, Erlangen 1978
3. R. Reichle, Diplomarbeit, Erlangen 1982
4. R.R. Hewitt and T.T. Taylor, Phys. Rev. 125(1962)524
5. W. Engel, W. Klinger and W. Witthuhn, Hyperfine Interactions 9(1981)247