1. Brewer, A. W., Quart. J. Roy. Met. Soc., 75, 351 (1949).
2. Dobson, G. M. B., Proc. Roy. Soc., A, 236, 187 (1956).
3. Stewart, N. G., Osmond, R. G. D., Crooks, R. N., and Fisher, E. M., A.E.R.E. publication, AERE HP/R 2354 (1957).
4. Machta, L., paper presented at Symposium on “Low-Level Irradiation”, Amer. Assoc. Adv. Sci., Indianapolis, Indiana (December 30, 1957).
5. Storebø, P. B., J. Meteor., 17, 547 (1960).