1. Hevesy, G., “Radioactive Indicators” (Interscience Publishers, Inc., New York, 1948). Peacock, W. C., et al., J. Clin. Invest., 25, 605 (1946).
2. Livingood, J. J., and Seaborg, G. T., Phys. Rev., 54, 51 (1938).
3. Govaerts, J., Bull. Soc. Roy. Sci. Liège, 12, 555 (1943).
4. Livingood, J. J., and Seaborg, G. T., Phys. Rev., 55, 1268 (1939); see also ref. 2.