1. Alazraki, G. and Couturier P.: 1971,Astron. Astrophys. 13, 380.
2. Asbridge, J. R., Bame, S. J. and Feldman, W. C.: 1973,Trans. Am. Geophys. Union 54, 440.
3. Belcher, J. W.: 1971,Astrophys. J. 168, 509.
4. Bollea, D., Formisano, V., Hedgecock, D. C., Moreno, G. and Palmiotto, F.: 1972,Proc. Asilomar Solar Wind Conf., NASA SP-308, p. 588.
5. Bretherton, F. P. and Garrett, C. J. R.: 1968,Proc. Roy. Soc. London A302, 529.