1. Actor A.,Höhler G., A Collection of Pion-Nucleon Scattering Formulas. Handbook of Pion-Nucleon Scattering, Part C, University of Karlsruhe.
2. Goldberger M. L., Miyazawa H., Oehme R., Phys. Rev.99 (1955), 986;
3. Hamilton J., Woolcock W. S., Rev. Mod. Phys.35 (1963), 737.
4. Pietarinen E., Nuovo Cim.12A (1972), 522.
5. Hendrick R. E., Lautrup B., Phys. Rev.D 11 (1975), 529.