1. Abramowitz, M. and Stegun, I. A. (eds.): 1972, Handbook of Mathematical Functions, Dover, New York, p. 228.
2. Aly, J. J.: 1984, Astrophys. J. 283, 349.
3. Aly, J. J.: 1991, Astrophys. J. 375, L61.
4. Bondi, H.: 1952, Astrophys. J. 112, 195.
5. Gibson, S. and Bagenal, F.: 1995, J. Geophys. Res. 100, 19685.