@inproceedings{
    bm2,
    author = "Back, R.J.R. and Mannila, Heikki",
    booktitle = "Proceedings of the ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing",
    year = "1982",
    pages = "111-120",
    title = "A refinement of Kahn's semantics to handle non-determinism and communication"
}