1. Jacchia, L. G., Nature, 183, 1662 (1959).
2. Jacchia, L. G., Spec. Rep. No. 62 (Smithsonian Inst., Mass., 1961).
3. Nicolet, M., Physics of the Upper Atmosphere, Chapter 2, edit. by Ratcliffe, J. A. (Academic Press, London, 1960).
4. Cole, K. D., Proc. Intern. Symp. Cosmic Rays and Earth Storm, Kyoto (in the press).
5. Cole, K. D., Austral. J. Phys., 15 (in the press).