@inproceedings{Gibbons2002:Superposition,
  title = "Towards a Colimit-Based Semantics for Visual Programming",
  author = "Jeremy Gibbons",
  year = "2002",
  booktitle = "Coordination Models and Languages",
  month = "apr",
  pages = "166--173",
  series = "Lecture Notes in Computer Science",
  url = "http://www.cs.ox.ac.uk/people/jeremy.gibbons/publications/superposition-extended.pdf",
  volume = "2315",
}