Techniques for one-loop calculations in constrained differential   renormalization
  We describe in detail the constrained procedure of differential renormalization and develop the techniques required for one-loop calculations. As an illustration we renormalize Scalar QED and show that the two-, three- and four-point Ward identities are automatically satisfied. 
F. del Aguila, A. Culatti, R. Munoz-Tapia and M. Perez-Victoria