The Quantum Action Principle in the framework of Causal Perturbation   Theory
  In perturbative quantum field theory the maintenance of classical symmetries is quite often investigated by means of algebraic renormalization, which is based on the Quantum Action Principle. We formulate and prove this principle in a new framework, in causal perturbation theory with localized interactions. Throughout this work a universal formulation of symmetries is used: the Master Ward Identity. 
Ferdinand Brennecke and Michael Duetsch