@article{Hin99Polb,
  title = "Polytypic Functions Over Nested Datatypes",
  author = "Hinze, Ralf",
  year = "1999",
  journal = "Discrete Mathematics and Theoretical Computer Science",
  month = "sep",
  number = "4",
  pages = "193-214",
  url = "http://www.dmtcs.org/dmtcs-ojs/index.php/dmtcs/article/view/109",
  volume = "3",
}