1. See,e.g.,C. Lovelace:Proc. of the Heidelberg Conference on Elementary Particles (September 1967) (Amsterdam, 1968). Most references are contained therein.
2. R. H. Dalitz:Proc. of the Oxford Conference on Elementary Particles (1965) (Rutherford High-Energy Laboratory, AERE Harwell, 1966); referred to as DI.
3. R. H. Dalitz:Proc. of the XIII Intern. Conference on High-Energy Physics, Berkeley, 1966 (Berkeley and Los Angeles, 1967); referred to as DII.
4. A. Donnachie, R. Kirsopp andC. Lovelace:Phys. Lett.,26, B 161 (1968).
5. C. Lovelace: invited paper, Proc. of the Topical Conference on $$\pi \mathcal{N}$$ scattering, Irvine, Calif. (December 1967).