J. M. Ngoko Djiokap, E. Foumouo, M. G. Kwato Njock, X. Urbain, and B. Piraux, “Electron-impact ionization excitation of helium in the quasiphoton regime,” Phys. Rev. A 81, 042712 (2010).
J. M. Ngoko Djiokap, E. Foumouo, M. G. Kwato Njock, X. Urbain, and B. Piraux, “Electron-impact ionization excitation of helium in the quasiphoton regime,” Phys. Rev. A 81, 042712 (2010).