1. A stationary approach in the abstract theory of scattering;Birman;Dokl. Akad. Nauk.,1964
2. Perturbation of self-adjoint transformations;de Branges;Amer. J. Math.,1962
3. Mathematical problems arising in the quantum mechanical scattering theory of a three particle system;Fadeev;Trudy Mat. Inst. Steklov.,1963