1. Jerome Kohl, René D. Zentner, and Herbert R. Lukens, Radioisotope Applications Engineering, p. 168, D. Van Nostrand Co. Inc. Princeton, N. J. (1961).
2. J. B. Hoag, Nuclear Reactor Experiments, J. B. Hoag, ed., p. 32, D. Van Nostrand Co. Inc. Princeton, N. J. (1958).