1. E. P. Wigner, “Proceedings of the Fourth Canadian Mathematical Congress” ( University of Toronto Press, Toronto 1957 ), p. 174
2. E. P. Wigner, Ann. Math. 67, 325 (1958)
3. F. J. Dyson, J. Math.Phys. J, 140 (1962)
4. H. S. Leff, Phys. Rev. 136, A355 (1964); J. Math. Phys. 5, 756 (1964); J. Math. Phys. 5, 763 (1964)
5. D. Fox and P. B. Kahn, Phys.Rev. 134, B1151 1964)