1. Existence conditions for wave operators;Birman;Izv. Akad. Nauk. SSSR. Ser. Mat.,1963
2. Existence conditions for wave operators
3. Perturbations of continuous spectrum of a singular elliptic operator under the change of the boundary and boundary condition;Birman;Vest. Leningrad. Univ. Mat. Mekh. Astronom.,1962
4. Scattering Theory;Lax,1967
5. Wave operators and asymptotic solutions of wave propagation problems of classical physics;Wilcox;Arch. Rat. Mech. Anal.,1966