@article{BlasiusToenjes2009,
  author    = {Bernd Blasius and Ralf Toenjes},
  title     = {Zipf's Law in the popularity distribution of chess openings},
  doi       = {10.1103/Physrevlett.103.218701},
  url       = {http://prl.aps.org/},
  year      = {2009},
}