@inproceedings{Gibbons2008:Unfolding,
  title = "Unfolding Abstract Datatypes",
  author = "Jeremy Gibbons",
  year = "2008",
  booktitle = "Mathematics of Program Construction",
  month = "jul",
  url = "http://www.comlab.ox.ac.uk/jeremy.gibbons/publications/adt.pdf",
}