Schneider-Jacoby, Martin, Peter Frenzel, Harald Jacoby, Gerhard Knötzsch, and Karl-Heinz Kolb. 2013. “The Impact of Hunting on a Protected Species, the Whooper Swan Cygnus Cygnus at Lake Constance”. Wildfowl, April, 378-82. https://tidsskrift.dk/Wildfowl/article/view/154939.