@article{FritzEhlertLeutner2018,
  author    = {Annemarie Fritz and Antje Ehlert and Detlev Leutner},
  title     = {Arithmetische Konzepte aus kognitiv-entwicklungspsychologischer Sicht},
  journal   = {Journal f{\"u}r Mathematik-Didaktik},
  volume    = {39},
  number    = {1},
  pages     = {7 -- 41},
  doi       = {10.1007/s13138-018-0131-6},
  year      = {2018},
}