1. Collins, R. Eugene, “The continuum and wave mechanics,” Ph.D. dissertation, Texas A&M University, 1954.
2. Barut, A. O.,Electrodynamics and Classical Theory of Fields and Particles (Macmillan, New York, 1964).
3. Riesz, F., and B. Sz-Nagy,Functional Analysis, translated by L.F. Boron (Ungar, New York, 1955). Also see T.F. Jordan,Linear Operators for Quantum Mechanics (Wiley, New York, 1969), p. 10.
4. Stone, M. H.,Linear Transformations in Hilbert Space (American Mathematical Society, New York, 1932). Also see T.F. Jordan,ibid., p. 52.
5. Collins, R. Eugene, “The mathematical basis of quantum mechanics,”Lett. Nuovo Cimento 18 (18) (1977).