@misc{Nagel_Karl_Fossilium,
 author={Nagel, Karl},
 howpublished={online},
 publisher={W. Junk},
 language={Tekst niem.},
 type={czasopismo},
 title={Fossilium Catalogus. II, Plantae. Pars 8: K. Nagel, Betulaceae},
 keywords={czasopisma, paleontologia, skamieliny, brzozowate},
}