@techreport{HamacherSchoebel2000,
  author    = {H.W. Hamacher and A. Sch{\"o}bel},
  title     = {Design of Zone Tariff Systems in Public Transportation},
  institution = {Fraunhofer (ITWM)},
  series    = {Berichte des Fraunhofer-Instituts f{\"u}r Techno- und Wirtschaftsmathematik (ITWM Report)},
  number    = {21},
  year      = {2000},
  url  = {http://nbn-resolving.de/urn:nbn:de:hbz:386-kluedo-12843},
}