@misc{Profus_Piotr_Numbers_1998,
 author={Profus, Piotr},
 volume={54},
 number={3},
 copyright={Creative Commons Attribution BY 3.0 PL license},
 address={Kraków},
 journal={Let's protect Our Indigenous Nature},
 howpublished={online},
 year={1998},
 publisher={Institute of Nature Conservation of the Polish Academy of Sciences},
 language={pol},
 type={Text},
 title={Numbers and territorial expansion of the breeding population of the Whooper Swan Cygnus cygnus in Central Europe},
 URL={http://www.rcin.org.pl/Content/118096/PDF/KR038_109441_r1998-t54-no3_ChPO-Profus-7-22.pdf},
 keywords={Whooper Swan, Cygnus cygnus},
}