1. H. Cheng andT. T. Wu:Phys. Rev. Lett.,24, 1456 (1970).
2. H. Cheng andT. T. Wu:High-energy scattering in ϕ 3-theory and the breakdown of eikonal approximation I, II, DESY-Reports No. 71/13, 71/16 (1971).
3. H. Cheng andT. T. Wu.:Regge poles for large coupling constants I, II, DESY-Reports 71/17, 71/31 (1971).
4. G. C. Wick:Phys. Rev.,96, 1124 (1954);R. E. Cutkosky:Phys. Rev.,96, 1135 (1954);N. Nakanishi:Phys. Rev. 147, 1153 (1966);Progr. Theor. Phys. 38, 226 (1967).
5. Reviews have been given byN. Nakanishi:Suppl. Progr. Theor. Phys. No 43 (1969);