1. Time delay has been introducted previously in a similar way by F.T. Smith: Phys. Rev. fff, 349(1960). Time delay funvtions computed for particular potentials are given in R. J. LeRoy, R. B. Bernstein: J. Chem. Phys. 54, 5114 (1971).
2. Gel’fand and shilov ( 1964, Vol. 1).
3. Taylor (1972, chapter 12).
4. N.G. van Kampen, Phys. Rev. 91, 1267 (1953), Section II [for odd/ all statements are for — S 1(p)].
5. N.G. van Kampen, Physica (Utrecht) 20, 115 (1954).