@article{KoehlerRaudies1997,
  author    = {K{\"o}hler, Egon and Raudies, Monika},
  title     = {Gedanken zur Weiterentwicklung des Mathematikunterrichtes in der Grundschule},
  issn      = {0945-6643},
  year      = {1997},
  language  = {de}
}
@article{KoehlerRaudies1997,
  author    = {K{\"o}hler, Egon and Raudies, Monika},
  title     = {Zuf{\"a}lle und Geometrie im Unterricht},
  year      = {1997},
  language  = {de}
}