1. V. De Alfaro andT. Regge:Potential Scattering (North Holland, Amsterdam, 1965).
2. M. L. Goldberger andK. Watson:Collision Theory (Wiley, New York, N. Y., 1964).
3. B. Symon:Ann. Math.,97, 247 (1973).
4. M. Reed andB. Symon:Methods of Modern Mathematical Physics, Vol.3, 4 (Academic Press, New York, N.Y., 1978).
5. A. Arseniev:Singular Potentials and Resonances (MGU, Moscow, 1974).