Abstract
In this chapter we return to scattering theory and set the foundation for approximation methods in calculating the scattering amplitude. We also address the problem of solving the Schrodinger equation for scattering in other than the coordinate representation. We convert the Schrodinger equation into an integral equation for the scattering amplitude and discuss ways of solving such integral equations. In the process we apply the formalism to electronatom scattering and nucleon-nucleon scattering.