@misc{Steffen_Hans_(1882–1945)_Vegetationskunde_1931,
 author={Steffen, Hans (1882–1945)},
 copyright={Public Domain},
 address={Jena},
 howpublished={online},
 year={1931},
 publisher={Verlag von Gustav Fischer},
 language={ger},
 title={Vegetationskunde von Ostpreußen},
 type={Text},
 URL={http://www.rcin.org.pl/Content/207264/PDF/KR171_229184_Steffen-1931_Vegetationskunde-Ostpreu%C3%9Fen.pdf},
}