1. W. Feller,An Introduction to Probability Theory and its Applications(John Wiley & Sons, Inc., New York, 1959), 2nd edition, Vol. 1, p. 208.
2. e−1∕(k+1)≈1−(k+1)−1 = (k∕k+1) = β
3. See reference 1, p. 214.
4. R. D. Evans,The Atomic Nucleus(McGraw-Hill Book Company, Inc., New York, 1955), p. 769.
5. See reference 4, p. 807, Eq. (3.22).