@incollection{Kortenkamp2017,
  author    = {Ulrich Kortenkamp},
  title     = {Raum und Form},
  booktitle = {Basiswissen Lehrerbildung: Mathematik unterrichten},
  editor    = {Maike Abshagen and B{\"a}rbel Barzel and J{\"u}rg Kramer and Thomas Riecke-Baulecke and Bettina R{\"o}sken-Winter and Christoph Selter},
  year      = {2017},
}