@article{Gibbons96:Third,
  title = "The Third Homomorphism Theorem",
  author = "Jeremy Gibbons",
  year = "1996",
  journal = "Journal of Functional Programming",
  note = "Earlier version appeared in C.\,B.\,Jay, editor, {\it Computing: The Australian Theory Seminar}, Sydney, December~1994, p.\,62--69",
  number = "4",
  pages = "657--665",
  url = "http://www.cs.ox.ac.uk/people/jeremy.gibbons/publications/thirdht.ps.gz",
  volume = "6",
}