1. M. Kac,Am. Math. Monthly 54 (1957).
2. M. Dresden and F. Feiock,J. Stat. Phys. 4:111 (1972).
3. A. Muriel,Am. J. Phys. 45:701 (1977).
4. J. von Neumann,The Mathematical Foundations of Quantum Mechanics (Princeton University Press, Princeton, N.J., 1955), Chapter VI.
5. G. Emch,Helv. Phys. Acta 45:1049 (1972); Whitten-Wolfe and G. Emch,Helv. Phys. Acta 49:45 (1976).