Keitel, Christoph H. Division Prof. Dr. Christoph H. Keitel, MPI for Nuclear Physics, Max Planck Society;
http://link.aps.org/doi/10.1103/PhysRevA.51.1420 (Publisher version)
Keitel, C. H., & Knight, P. L. (1995). Monte Carlo classical simulations of ionization and harmonic generation in the relativistic domain. Physical Review. A, 51(2), 1420-1430. doi:10.1103/PhysRevA.51.1420.