@article{BirdPaterson99:deBruijn,
  author = "Richard S. Bird and Ross Paterson",
  doi = "10.1017/S0956796899003366",
  journal = "Journal of Functional Programming",
  number = "1",
  pages = "77--91",
  title = "de~{B}ruijn Notation as a Nested Datatype",
  url = "http://www.comlab.ox.ac.uk/people/richard.bird/online/BirdPaterson99DeBruijn.pdf",
  volume = "9",
  year = "1999",
}