1. Gabbard, F., Bischsell, H., and Bonner, T. W., Nucl. Phys., 14, 277 (1959).
2. Watt, B. E., Phys. Rev., 87, 1037 (1952).
3. Etherington, H. (editor), Nuclear Engineering Handbook (McGraw-Hill, New York, 1958).
4. Isbin, H. S., Introductory Nuclear Reactor Theory, 234 (Reinhold, New York, 1963).
5. Nucleonics, 20, 159 (Table 3).