1. D. Amati, S. Fubini andA. Stanghellini:Nuovo Cimento,26, 896 (1962); hereafter referred to as ASF.
2. Post-deadline paper at the A.P.S. Meeting, January 1963, presented byS. J. Lindenbaum (unpublished);
3. Bologna, CERN, Liverpool and Michigan Collaboration: private communication byG. Giacomelli;
4. S. Brandt et al.: CERN and Ecole Polytechnique Collaboration (CERN preprint).