@inproceedings{BirdMeertens98:Nested,
  title = "Nested Datatypes",
  author = "Richard S. Bird and Lambert Meertens",
  year = "1998",
  address = "Marstrand, Sweden",
  booktitle = "LNCS~1422: Proceedings of Mathematics of Program Construction",
  editor = "Johan Jeuring",
  month = "jun",
  pages = "52--67",
  publisher = "Springer-Verlag",
  url = "http://www.cs.ox.ac.uk/people/richard.bird/online/BirdMeertens98Nested.pdf",
}