S. E. Homola, Simulation of ultra-high energy photon propagation in the geomagnetic field, Computer Physics Communications, vol.173, issue.1-2, p.71, 2005.
DOI : 10.1016/j.cpc.2005.07.001

M. Risse, Photon air showers at ultra-high energy and the photonuclear cross-section, Czechoslovak Journal of Physics, vol.33, issue.S1, p.327, 2006.
DOI : 10.1007/s10582-006-0166-7