@article{SpahnPetzschmannSchmidtetal.2001,
  author    = {Spahn, Frank and Petzschmann, Olaf and Schmidt, J{\"u}rgen and Sremcevic, Miodrag and Hertzsch, Jan-Martin},
  title     = {About the viscosity of granular gases : the force-free case versus granular gases under Keplarian differential rotation},
  isbn      = {3-540-41458-4},
  year      = {2001},
  language  = {en}
}