@misc{Harrison,
  author = "John Harrison",
  title = "Formula for the number of derangements",
  note = "Available at \url{https://github.com/jrh13/hol-light/blob/master/100/derangements.ml}"
}

@misc{wikipedia:derangement,
  author = "Wikipedia",
  title = {{Derangement --- Wikipedia{,} The Free Encyclopedia}},
  year = "2015",
  note = "\url{https://en.wikipedia.org/w/index.php?title=Derangement&oldid=686842426}, [Online; accessed 18-November-2015]"
}

@misc{wikipedia:fixpunktfreie-permutation,
  author = "Wikipedia",
  title = {{Fixpunktfreie Permutation --- Wikipedia{,} Die freie Enzyklopädie}},
  year = "2015",
  note = "\url{https://de.wikipedia.org/w/index.php?title=Fixpunktfreie_Permutation&oldid=146073460}, [Online; accessed 18-November-2015]"
}

@misc{wikipedia:rencontres-numbers,
  author = "Wikipedia",
  title = {{Rencontres numbers --- Wikipedia{,} The Free Encyclopedia}},
  year = "2014",
  note = "\url{https://en.wikipedia.org/w/index.php?title=Rencontres_numbers&oldid=616214357}, [Online; accessed 18-November-2015]"
}
