1. The digital ionospheric sounding system network of the US Air Force Weather Service UAG-##;Buchau,1994
2. Occurrence of AE and Dst geomagnetic index levels and the selection of the quietest days in a year;Campbell;J. Geophys. Res.,1979
3. The IPS monthly T index;Caruana,1990
4. The absorption and dissociative or ionising effect of monochromatic radiation in an atmosphere on a rotating Earth;Chapman,1931
5. The absorption and dissociative or ionising effect of monochromatic radiation in an atmosphere on a rotating Earth;Chapman,1931