H. Al-Shamma, S., سالم, M. I. Azawi, and مزاحم. “A Suitable Analytical Formula for the K Shell Ionization Cross Section of Carbon and Potassium Atoms by Electron Impact”. Journal of Education and Science (JES), vol. 26, no. 3, Aug. 2013, pp. 18-22, doi:10.33899/edusj.2013.89914.