@book{Kasper1992,
  author    = {Kasper, Uwe},
  title     = {On the phenomenological description of particle and entropy creation},
  series = {Preprint / Universit{\"a}t Potsdam, Fachbereich Mathematik},
  volume    = {1992, 07},
  journal   = {Preprint / Universit{\"a}t Potsdam, Fachbereich Mathematik},
  publisher = {Univ.},
  address   = {Potsdam},
  pages     = {10 S.},
  year      = {1992},
  language  = {en}
}
@book{Kasper1992,
  author    = {Kasper, Uwe},
  title     = {Particle and entropy creation in cosmology},
  series = {Preprint / Universit{\"a}t Potsdam, Fachbereich Mathematik},
  volume    = {1992, 13},
  journal   = {Preprint / Universit{\"a}t Potsdam, Fachbereich Mathematik},
  publisher = {Univ.},
  address   = {Potsdam},
  pages     = {5 Bl.},
  year      = {1992},
  language  = {en}
}