@article{Bulwahn15b,
  title = {Cardinality of Set Partitions},
  author = {Lukas Bulwahn},
  year = {2015},
  url = {http://afp.sourceforge.net/entries/Card_Partitions.shtml},
  researchr = {https://researchr.org/publication/Bulwahn15b},
  cites = {0},
  citedby = {0},
  journal = {Archive of Formal Proofs},
  volume = {2015},
}