@incollection{Nieuwkoop2010,
  author    = {Pieter D. Nieuwkoop},
  title     = {The systematic description of the internal development of Xenopus laevis},
  booktitle = {Normal table of Xenopus laevis (Daudin)},
  edition   = {[2. Repr. d.] 1967},
  year      = {2010},
}