@misc{Rösler_Alfred_The_1981,
 author={Rösler, Alfred},
 volume={37},
 editor={Research Centre for the Protection of Nature and Natural Resources of the Polish Academy of Sciences},
 number={5},
 copyright={Creative Commons Attribution BY 3.0 PL license},
 journal={Let's protect Our Indigenous Nature},
 address={Warszawa},
 address={Kraków},
 howpublished={online},
 year={1981},
 publisher={Państwowe Wydawnictwo Naukowe},
 language={pol},
 title={The mute swan in the Sławsko Lake District},
 type={Text},
 URL={http://rcin.org.pl./Content/83754/PDF/KR038_106452_r1981-t37-no5_ChPO-Rosler-68-72.pdf},
 keywords={mute swan, Sława Lakeland, Cygnus olor},
}