Geometric quantization on homogeneous spaces and the meaning of   `inequivalent' quantizations
  Consideration of the geometric quantization of the phase space of a particle in an external Yang-Mills field allows the results of the Mackey-Isham quantization procedure for homogeneous configuration spaces to be reinterpreted. In particular, a clear physical interpretation of the `inequivalent' quantizations occurring in that procedure is given. 
M. A. Robson