1. von Neumann, J.: Mathematische Grundlagen der Quantenmechanik (1932). English Translation: Mathematical Foundations of Quantum Mechanics. Princeton University Press, Princeton (1955)
2. Pauli, W.: Die allgemeinen Prinzipien der Wellenmechanik (1933). English Translation: General Principles of Quantum Mechanics. Springer, Berlin (1980)
3. Mittelstaedt, P.: The Interpretation of Quantum Mechanics and the Measurement Process, Sect. 4.3(b). Cambridge University Press, Cambridge (1998)
4. Busch, P., Lahti, P.J., Mittelstaedt, P.: The Quantum Theory of Measurement, 2nd Revised Edition, Sect. III.6.2. Springer, Berlin (1996)
5. Dirac, P.A.M.: The Principles of Quantum Mechanics, pp. 46–47. Clarendon Press, Oxford (1958)