1. For instance, see R. Behrisch, W. Heiland, W. Poschenrieder, P. Staib, H. Verbeek (eds.):Ion Surface Interaction, Sputtering and Related Phenomena (Gordon and Breach, London, New York, Paris 1973)
2. A.Benninghoven: Surface Sci.53, 596 (1975)
3. M.Prager: Appl. Phys.8, 361 (1975)
4. J. M. Rouberol, J. Guernet, P. Deschamps, J. P. Dagnot, J. M. Guyon de la Berge: In5th Int. Conf. X-Ray Optics and Microanalysis, Tübingen 1968 (Springer-Verlag, Berlin, Heidelberg, New York 1969) p. 311
5. H.Liebl: J. Vac. Sci. Technol.12, 385 (1975)