1. Dirac, P.A.M.: The Principles of Quantum Mechanics, pp. 4ff, 253ff. Clarendon Press, Oxford (1958)
2. Barut, A.O., Bracken, A.J.: Phys. Rev. D 23(10), 2454–2463 (1981)
3. Huang, K.: Statistical Mechanics, p. 75ff. Wiley Eastern, New Delhi (1975)
4. Hestenes, D.: Found. Phys. 20(10), 1213–1232 (1990)
5. Sidharth, B.G.: Chaotic Universe: From the Planck to the Hubble Scale. Nova Science, New York (2001)