1. Dirac, P.A.M.: The quantum theory of the electron. Proc. R. Soc. Lond. A 177, 610–624 (1928)
2. Heisenberg, W.: The Physical Principles of the Quantum Theory (trans. Eckhart, K., Hoyt, F.C.). Dover, New York, reprint 1949 (1930)
3. Dirac, P.A.M.: The Principles of Quantum Mechanics, 4th edn. Clarendon, Oxford, reprint 1995 (1930)
4. Einstein, A.: What is the theory of relativity. The London Times, 28 November, 1919; in Einstein, A.: Ideas and Opinions. Bonanza Books, New York, 1954 (1919)
5. Zeilinger, A.: A foundational principle for quantum mechanics. Found. Phys. 29(4), 63 (1999)