@article{
  ns_sem_benveniste_bourke_caillaud_pouzet,
  title={Non-Standard Semantics of Hybrid Systems Modelers},
  author={Benveniste, Albert and Bourke, Timothy and
          Caillaud, Benoıt and Pouzet, Marc},
  year={2011},
  language={en}
}
@inbook{
  opsem_lee_zheng,
  title={Operational Semantics of Hybrid Systems},
  ISBN={978-3-540-25108-8},
  author={Lee, Edward A. and Zheng, Haiyang},
  year={2005},
  language={en}
}