1. G.B. Arfken, H.J. Weber, Mathematical Methods for Physicists, 6th edn. (Elsevier, MA, 2005)
2. C.J. Foot, Atomic Physics (Oxford University Press, NY, 2005)
3. W. Greiner, Quantum Mechanics: An Introduction, 4th edn. (Springer, Heldelberg, 2001)
4. D.J. Griffiths, Am. J. Phys. 50, 698 (1982)
5. D.J. Griffiths, Introduction to Quantum Mechanics, 2nd edn. (Pearson Prentice Hall, NJ, 2005)