1. B. D. Sawicka and J. A. Sawicki, Topics in current physics (Springer, Berlin, 1981) 25, p. 139.
2. I. Deszi, J. Physique Colloque 41 (1980) C1?17.
3. H. de Waard, J. Physique Colloque, Handbook on ion implantation in M�ssbauer spectroscopy, in preparation.
4. J. C. Stevens and V. S. Stevens, to be published.
5. J. Lindhard, M. Scharff and H.E. Schi�tt, Mat. Fys. Medd. Dan. Vid. Selsk. 33 (1963) no. 14.