Modified Kolbensvedt model for the electron impact K-shell ionization cross-sections of atoms and ionsM. A. Uddin, A. K.F. Haque, K. R. Karim, A. K. Basak and F. B. MalikEur. Phys. J. D, 37 3 (2006) 361-369DOI: https://doi.org/10.1140/epjd/e2005-00305-4