@article{Nipkow08a,
  title = {Fun With Functions},
  author = {Tobias Nipkow},
  year = {2008},
  url = {http://afp.sourceforge.net/entries/FunWithFunctions.shtml},
  note = {Formal proof development},
  researchr = {https://researchr.org/publication/Nipkow08a},
  cites = {0},
  citedby = {0},
  journal = {Archive of Formal Proofs},
  volume = {2008},
}