1. D. M. GRODZINSKI, O. F. NEMETS, A. E. MELENEVSKI, V. A. TIHI, Vestn. Selskohoz. Nauki, 7 (1983) 47.
2. D. A. DOHAN, K. G. STANDING, Physics in Industry, Pergamon Press, Oxford and New York, 1976, p. 509.
3. B. SUNDOVIST, L. GOENCZI, I. KOERSNER, R. BERGMAN, U. LINDH, Ion Beam Surface Analysis, Plenum Press, New York and London, 1976, p. 945.
4. GH. DUMITRU, Ph. D. Thesis, Polytechnical Institute, Bucharest, 1983.