H. Al-Shamma, S., سالم, I. Azawi, M., مزاحم, H. Ismail, L. and لبنى 1970. An analytical expression for the K shell ionization cross section of some heavy atomic elements by electron impact. Journal of Education and Science (JES). 24, 4 (Jan. 1970), 123–130. DOI:https://doi.org/10.33899/edusj.1970.58959.