1. F. Calogero:Variable Phase Approach to Potential Scattering (New York, 1967). See alsoF. Calogero:Scattering Theory: New Methods and Problems in Atomic, Nuclear and Particle Physics, edited byA. D. Barut (London, 1970), p. 3–46 and 47–51.
2. Ref. (1)F. Calogero:Variable Phase Approach to Potential Scattering (New York, 1967). and references therein.
3. S. R. Singh:Lett. Nuovo cimento,12, 482 (1973).
4. T. Kato:Phys. Rev.,80, 475 (1950).
5. R. Sugar andR. Blakenbecher:Phys. Rev.,141, 1454 (1966).