A. J. Mannucci, B. T. Tsurutani, M. A. Abdu, W. D. Gonzalez, A. Komjathy, E. Echer, B. A. Iijima, G. Crowley and D. Anderson, “Superposed epoch analysis of the dayside ionospheric response to four intense geomagnetic storms”, Journal of Geophysical Research, 113, A00A02 (2008)
Akasofu, S.I. and Chapman, S. (1963) Space Sci. Rev. 2, 91