@article{Ballstaedt2007,
  author    = {Steffen-Peter Ballstaedt},
  title     = {Unterrichtsmaterial lerneffektiv gestalten},
  journal   = {P{\"a}dagogik},
  volume    = {59},
  number    = {11},
  pages     = {22 -- 25},
  year      = {2007},
}