@book{HaneltHolubekMoelleretal.2005,
  author    = {Martina Hanelt and Ines Holubek and Angelika M{\"o}ller and Ramona Schmidt and Irina Schultheiß and Reinhard Stamm},
  title     = {Duden Mathematik : Ausg. G, Gymnasium ; Klasse 6},
  isbn      = {3-89818-573-7},
  year      = {2005},
}