Bortolussi, Luca and Galpin, Vashti and Hillston, Jane and Tribastone, Mirco  Hybrid semantics for PEPA.   In:  Proceedings of the 7th International Conference on the Quantitative Evaluation of Systems (QEST).   IEEE, pp. 181-190.  ISBN 978-1-4244-8082-1      (2010)