Quantization of the Taub cosmological model with extrinsic time
  The paper addresses the quantization of minisuperspace cosmological models, with application to the Taub Model. By desparametrizing the model with an extrinsic time, a formalism is developed in order to define a conserved Schr\"{o}dinger inner product in the space of solutions of the Wheeler-De Witt equation. A quantum version of classical canonical transformations is introduced for connecting the solutions of the Wheeler-De Witt equation with the wave functions of the desparametrized system. Once this correspondence is established, boundary conditions on the space of solutions of the Wheeler-De Witt equation are found to select the physical subspace. The question of defining boundary conditions on the space of solutions of the Wheeler-De Witt equation without having reduced the system is examined. 
Gabriel Catren, Rafael Ferraro