Quantization of the Relativistic Particle
  We revise the problem of the quantization of relativistic particle, presenting a modified consistent canonical scheme, which allows one not only to include arbitrary backgrounds in the consideration but to get in course of the quantization a consistent relativistic quantum mechanics, which reproduces literally the behavior of the one-particle sector of the corresponding quantum field. At the same time this construction presents a possible solution of the well-known old problem how to construct a consistent quantum mechanics on the base of a relativistic wave equation. 
S.P. Gavrilov, D.M. Gitman