1. C M Davisson and R D Evans,Phys. Rev. 81, 104 (1951)
2. A L Conner, H F Atwater, E H Plassman and J H McCray,Phys. Rev. A1, 539 (1977)
3. B Goswami and N Chaudhuri,Phys. Rev. A7, 1912 (1973)
4. A H El-Kateb, A H Hassan and A S Abdul Hamid,1st Egyptian-British Conf. on Biophysics (Cairo University, 1987) p. 442
5. A H El-Kateb, A H Hassan, S A El-Hennawi and A S Abdul Hamid,Nucl. Sci. J. 26, 133 (1989)