1. A complete bibliography about the early works on the gauge fields can be found for instance inE. E. Abers andB. W. Lee:Phys. Rep.,9 C, No. 1 (November 1973).
2. C. Becchi, A. Rouet andA. Stora:Phys. Lett.,52 B, 344 (1974);Comm. Math. Phys.,42, 127 (1975).
3. G. ’t Hooft andM. Veltman:Diagrammar, CERN Report 73-9 (1973).
4. G. Curci andR. Ferrari:Nuovo Cimento,30 A, 155 (1975).
5. L. D. Faddeev andV. N. Popov:Phys. Lett.,25 B, 20 (1967).