@book{Witt2013,
  author    = {Witt, Kurt-Ulrich},
  title     = {Elementare Kombinatorik f{\"u}r die Informatik},
  isbn      = {978-3-658-00993-9},
  doi       = {10.1007/978-3-658-00994-6},
  institution = {Fachbereich Informatik},
  year      = {2013},
  language  = {de}
}