Hartmann, G. K. MPI for Aeronomy, Max Planck Institute for Solar System Research, Max Planck Society;
Leitinger, R., Jakowski, N., Davies, K., Hartmann, G. K., & Feichter, E. (2000). Ionospheric electron content and space weather: some examples. Physics and Chemistry of the Earth, 25(8), 629-634.