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2. J. M. Blatt and V. F. Weisskopf, Theoretical Nuclear Physics (Wiley, New York, 1952), pp. 525–528.
3. V. Bargmann, Ann. Math.
59, 1 (1954).
4. A. Peres, Quantum Theory: Concepts and Methods (Kluwer, Dordrecht, Netherlands, 1993), pp. 245–249.
5. F. A. Kaempffer, Concepts in Quantum Mechanics (Academic Press, New York, 1965).