1. D. Randall and S. John, Nucleonics,16, 82 (1958).
2. S. Kaplan et al., Paper No. 28/p/271 presented by the USA at the Third International Conference on the Peaceful Uses of Atomic Energy [Russian translation], Geneva (1964).
3. I. S. Postnikov and E. F. Sabaev, Izv. Akad. Nauk BSSR, No. 3, 46 (1947).
4. S. Margolis and S. Kaplan, WAPD-T-1156, (June, 1960).
5. E. Gyftopoulos, Nucl. Sci. and Engng.,10, 254 (1961).