@inproceedings{CD,
  title = "Interacting quantum observables",
  author = "Bob Coecke and Ross Duncan",
  year = "2008",
  booktitle = "Proceedings of the 37th International Colloquium on Automata, Languages and Programming (ICALP)",
  note = "Extended version: {a}rXiv:quant-ph/09064725",
  series = "Lecture Notes in Computer Science",
}