1. G. Källén andW. Pauli:Mat. Fys. Medd. Dan. Vid. Selsk.,30, no. 7 (1955).
2. A physical interpretation also in this case may however be possible by changing the connection betweenS matrix and Hilbert space (private communication ofB. Ferretti; see alsoR. J. N. Phillips:Nuovo Cimento,1, 823 (1955)).
3. W. Heisenberg:Nucl. Phys.,4, 532 (1957).
4. V. Glasser:Proc. of the Annual Int. Conf. on High Energy Phys. at CERN (1958), p. 132.
5. R. Ascoli andE. Minardi:Nuovo Cimento,8, 951 (1958) andNucl. Phys.,9, 242 (1958–59).