@book{SchroederBoedekerEdelstein2000,
  author    = {Eberhard Schr{\"o}der and Katja B{\"o}deker and Wolfgang Edelstein},
  title     = {The development of concrete thought : a manual including measurement procedures and descriptive analyses},
  volume    = {67},
  isbn      = {3-87985-079-8},
  year      = {2000},
}