1. J. Le Traon and G. Seibel, Internat. J. Appl. Rad. Isotopes,14, 365 (1963).
2. Yu. P. Betin, Atomnaya Énergiya,18, 516 (1965).
3. C. Mellish, Research,12, 212 (1959).
4. J. Cameron and J. Rhodes, Nucleonics,19, No. 6, 53 (1961).
5. G. Seibel, J. Le Traon, and P. Martinelli, Rev. Univ. Mines,17, 260 (1961).