1. R. H. Young, unpublished.
2. E. H. Kennard,Phys. Rev. 31, 876 (1928).
3. E. H. Kennard,J. Franklin Inst. 207, 495 (1929).
4. E. C. Kemble,The Fundamental Principles of Quantum Mechanics (Dover, New York, 1958), esp. Sections 14a, b; 15; 33b; 41.
5. W. Pauli, Die allgemeinen Prinzipien der Wellenmechanik, inGeiger-Scheel Handbuch der Physik, Vol. 24, Part 1 (Springer, Berlin, 1933), Part A, p. 94 and Sections 9, 11.