@misc{Hertwig_Richard_(1850–1937)_Lehrbuch_1924,
 author={Hertwig, Richard (1850–1937)},
 copyright={Public Domain},
 address={Jena},
 howpublished={online},
 year={1924},
 publisher={Verlag von Gustav Fischer},
 language={ger},
 title={Lehrbuch der zoologie},
 type={Text},
 URL={http://www.rcin.org.pl/Content/186358/PDF/WA488_220782_19783_Hertwig-Lehrbuch.pdf},
 keywords={Zoology - history - development of morphology, Zoology - history - the theory of origin - Darwinian theory},
}