1. W.N. Cottingham, M. Lacombe, B. Loiseau, J.M. Richard, R. Vinh Mau, Phys. Rev. D, to be published.
2. Chapter 4. Dispersion Theoretic Approach
3. J. Hamilton, High energy physics, Vol. 1, p. 193.
4. G. Höhler, R. Strauss and H. Wunder, Karlsruhe preprint (1968) and the references cited therein.
5. Consistency between the low-energy pion-pion interaction and pion-nucleon scattering