1. G. Biczò, Proc. 7th Int.Vac.Congr. and 3rd Int.Conf.Solid Surf. (Vienna: Berger and Söhne ed. Dobrozemsky, A et al., 1977) Vol.I, pp.407–10.
2. G. Biczo, Prof.ECOSS I, Nederlands Tijdschrift voor Vacuum- techniek 16, 195 (1978).
3. G. Biczò and I. Lukovits, Int.J.Quantum Chem. 16, 31 (1979).
4. R. de L. Kronig and W.G. Penney, Proc.Roy.Soc. London A130, 499 (1931).
5. I. Tamm, Phys.Z.Soviet Union 1, 732 (1932), and Z. Physik 76, 849 (1932).