1. Osborne, R. V., Nature, 199, 144 (1963). Hill, C. R., Osborne, R. V., and Mayneord, W. V., “Studies of Alpha Radioactivity in Relation to Man”, paper given at Symp. Natural Radiation Environment, April 1963, Rice University (in the press).
2. Radford, E. P., and Hunt, V. R., Science (Jan. 1964).
3. Marsden, E., and Collins, M. A., Nature, 198, 962 (1963).
4. Dean, G., Brit. Med. J., 1599 (1961);
5. Med. J. Austral., 1003 (1962).