1. Pales, J., and Keeling, C. D., J. Geophys. Res. 70, 6053 (1965).
2. Cobb, W., and Wells, H. J., J. Atmos. Sci. 27, 814 (1970).
3. Junge, C. E., “Air Chemistry and Radioactivity,” Academic Press, New York, 1963.
4. Georgii, H. W., Bull. World Health Organiz. 40, 624 (1969).
5. Jaenike, R., and Junge, C. E., Beitr. Phys. Atmosphäre 40, 129 (1967).