1. J. M. Wilcox, Space Sci. Rev., 8, 258, 1968.
2. R. J. Markson, Symp. Elect. Processes and Problems in the Stratosphere and Mesosphere, IAGA Meeting, Madrid, 1969, published in Pure Appl. Geophys., 84, 161, 1971.
3. M. D. Lethbridge, J. Geophys. Res., 25, 5149, 1970.
4. A. J. Hundhausen, Coronal holes and high speed wind streams, ed. by J. B. Zirker, Colo. Assoc. Univ. Press, 1977. Also see other articles in this volume.
5. J. M. Wilcox, P. H. Scherer, L. Svalgaard, W. O. Roberts, and R. H. Olson, Science, 180, 185, 1973.