1. Toweles, S., in World Met. Org. Tech. Note, No. 70 (edit. by Murgatroyd, R. J., et al.), 79 (1965).
2. Bossalasco, M., and Elena, A. C., C. R. Acad. Sci., Paris, 256, 4491 (1963).
3. Gregory, J. B., J. Atmos. Sci., 22, 18 (1965).
4. Shapley, A. H., and Beynon, W. J. G., Nature, 206, 1242 (1965).
5. Lauter, E. A., and Entzian, G., Veroffentlichungen des NKGG der DDR, Reihn II, 1, 77 (1966).