@misc{Witkowski_Józef_Breeding_1989,
 author={Witkowski, Józef},
 volume={25},
 editor={Polska Akademia Nauk. Instytut Zoologii},
 editor={Państwowe Wydawnictwo Naukowe (1951–1992)},
 number={3},
 copyright={Creative Commons Attribution BY 3.0 PL license},
 address={Warszawa},
 journal={Acta Ornithologica},
 howpublished={online},
 year={1989},
 publisher={Państwowe Wydawnictwo Naukowe},
 language={eng},
 language={rus},
 language={pol},
 type={Text},
 title={Breeding biology and ecology of the marsh harrier Circus aeruginosus in the Barycz valley, Poland},
 URL={http://rcin.org.pl/miiz/Content/42393/PDF/WA058_59180_P257-T25_Acta-Ornith-Nr-3-1.pdf},
 keywords={Marsh Harrier, ecology, breeding biology, Poland, Barycz Valley Landscape Park, birds, Circus aeruginosus, Accipitridae, Aves},
}