1. Cane, H. V., Sheeley, N. R., Jr., and Howard, R. A.: 1987, J. Geophys. Res. 92, 9869.
2. Dodson, H. W. and Hedeman, E. R.: 1981, Report UAG-80, World Data Center A for Solar-Terrestrial Physics, NOAA, Boulder Colorado.
3. Duffett-Smith, P. J., Purvis, A., and Hewish, A.: 1980, Monthly Notices Roy. Astron. Soc. 190, 891.
4. Eselevich, V. G. and Fainshtein, V. G.: 1989, Planetary Space Sci. 37, 1027.
5. Eselevich, V. G. and Fainshtein, V. G.: 1991a, Planetary Space Sci. (in press).