1. I. Kaplan:Nuclear Physics (Cambridge, Mass., 1955), p. 436.
2. M. Abramowitz andI. A. Stegun, Editors:Handbook of Mathematical Functions (Applied Mathematics Series 55, National Bureau of Standards, U.S., 1964), p. 686.
3. L. I. Schiff:Quantum Mechanics (New York, N. Y., 1955), p. 66.