Pseudoclassical Model of Spinning Particle with Anomalous Magnetic   Momentum
  A generalization of the pseudoclassical action of a spinning particle in the presence of an anomalous magnetic momentum is given. The action is written in reparametrization and supergauge invariant form. The Dirac quantization, based on the Hamiltonian analyses of the model, leads to the Dirac-Pauli equation for a particle with an anomalous magnetic momentum in an external electromagnetic field. Due to the structure of first-class constraints in that case, the Dirac quantization demands for consistency to take into account an operators ordering problem. 
D.M. Gitman and A.V.Saa