@article{Gwinner2011,
  author    = {Eberhard Gwinner},
  title     = {Untersuchungen {\"u}ber das Ausdrucks- und Sozialverhalten des Kolkraben (Corvus corax corax L.)},
  journal   = {Zeitschrift f{\"u}r Tierpsychologie},
  volume    = {21},
  number    = {6},
  pages     = {657 -- 748},
  year      = {2011},
}