@article{Hughes01:1,
  title = {Modal Operators for Coequations},
  author = {Jesse Hughes},
  year = {2001},
  url = {http://www.elsevier.com/gej-ng/31/29/23/73/23/show/Products/notes/index.htt#011},
  researchr = {https://researchr.org/publication/Hughes01%3A1},
  cites = {0},
  citedby = {0},
  journal = {Electronic Notes in Theoretical Computer Science},
  volume = {44},
  number = {1},
  pages = {205-226},
}