1. Mayneord, W. V., Anderson, W., Bentley, R. E., Burton, L. K., Crookall, J. O., and Trott, N. G., Nature, 182, 1473 (1958).
2. Anderson, W., Burton, L. K., and Crookall, J. O., Nature, 184, 89 (1959); 187, 108 (1960); 192, 1009 (1961).
3. Morgan, A., Rundo, J., Vandervell, H. D., and Emeleus, Miss V. M., Nature, 193, 1150 (1962).
4. Squire, Miss H. M., Middleton, L. J., Sansom, B. F., and Coid, R. C., Progress in Nuclear Energy, Ser. 6, 3, 69 (Pergamon Press, 1961).
5. Radioactivity in Milk, Rep. Agric. Res. Coun., ARCRL 6 (1961) and ARCRL 7 (1962).