@book{Abel1920-lp,
  author = "O. Abel",
  title = "Lehrbuch der Palaozoologie",
  year = 1920,
  publisher = "Verlag by Gustav Fischer, Jena",
  volume = 1,
  pages = "456-457",
  url = "https://books.google.com/books?hl=en&lr=&id=gidCAAAAIAAJ&oi=fnd&pg=PR1&dq=Abel+1920+Lehrbuch+der+Pal%C3%A4ozoologie&ots=yF5S9-U_ox&sig=ulorvj-SUlYq4g59qYDFPvpXUQI#v=onepage&q=Abel%201920%20Lehrbuch%20"
}