1. [12] L. Hörmander, The existence of wave operators in scattering theory, Math. Z. 146 (1976), no. 1, 69–91.
2. [13] L. Hörmander, The analysis of linear partial differential operators. IV, Grundlehren der Mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences], vol. 275, Springer-Verlag, Berlin, 1985.
3. [1] S. Agmon, Some new results in spectral and scattering theory of differential operators on ${\bf R}\sp{n}$, Séminaire Goulaouic-Schwartz (1978/1979), École Polytech., Palaiseau, 1979, Exp. No. 2, 11.
4. [2] P. Alsholm and T. Kato, Scattering with long range potentials, Partial differential equations (Proc. Sympos. Pure Math., Vol. XXIII, Univ. California, Berkeley, Calif., 1971), Amer. Math. Soc., Providence, R.I., 1973, pp. 393–399.
5. [3] W. O. Amrein, Ph. A. Martin, and B. Misra, On the asymptotic condition of scattering theory, Helv. Phys. Acta 43 (1970), 313–344.