1. M. Jammer,The Conceptual Development of Quantum Mechanics (McGraw-Hill, New York, 1966), Section 3.2.
2. B. L. Van der Waerden,Sources of Quantum Mechanics (Dover, New York, 1968).
3. S. Tomonaga,Quantum Mechanics (North-Holland, Amsterdam, 1962), Vol. 1, Chapter 3.
4. R. Becker and F. Sauter,Quantum Theory of Atoms and Radiation (Blaisdell, New York, 1964), Vol. II.
5. R. Eisberg,Fundamentals of Modern Physics (Wiley, New York, 1961), Chapter 8.