H. Al-Shamma, S., سالم, I. Azawi, M., مزاحم, H. Ismail, L., & 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), 123–130. https://doi.org/10.33899/edusj.1970.58959