1. J. Von Neumann, Ann. Math.,104, 570, 1931.
2. First noticed byJ. Von Neumann; seeK. O. Friedrichs, Mathematical Aspects of the Quantum Theory of Fields, New York, 1953, alsoL. Van Hove, Physica,18, 1451. 1952.
3. R. Haag andD. Kastler, J. Math. Phys.,5, 848, 1964.
4. R. Haag, Lectures in Theoretical Physics, Vol. 3, Summer Institute for Theoretical Physics, University of Colorado, Boulder, 1960, New York 1961.
5. R. Haag, Kgl. Den. Mat. Fys. Medd.,29, No. 12, 1955.