@article{CES,
  title = "Phase groups and the origin of non-locality for qubits",
  author = "Bob Coecke and Bill Edwards and Robert W. Spekkens",
  year = "2011",
  journal = "Electronic Notes in Theoretical Computer Science",
  note = "{a}rXiv:1003.5005",
  number = "2",
  pages = "15-36",
  volume = "270",
}