J. Chem. Phys.

Adamczyk, B., Boerboom, A. J. H., Schram, B. L., & Kistemaker, J. (1966). Partial ionization cross sections of He, Ne, H2 and CH4 for electrons from 20 to 500 eV. J. Chem. Phys., 44, 4640–4642.