Classical and quantum cosmology with two perfect fluids: stiff matter   and radiation
  In this work the homogeneous and isotropic Universe of Friedmann-Robertson-Walker is studied in the presence of two fluids: stiff matter and radiation described by the Schutz's formalism. We obtain to the classic case the behaviour of the scale factor of the universe. For the quantum case the wave packets are constructed and the wave function of the universe is found. 
F. G. Alvarenga, R. Fracalossi, R. C. Freitas and S. V. B.   Gon\c{c}alves
gr-qc astro-ph.CO hep-th