@inproceedings{Piazza:2008TD,
  author = "Piazza, Federico  and  Costa, Fabio",
  title = "{Space-time regions as "subsystems"}",
  doi = "10.22323/1.043.0032",
  booktitle = "Proceedings of From Quantum to Emergent Gravity: Theory and Phenomenology {\textemdash} PoS(QG-Ph)",
  year = 2008,
  volume = "043",
  pages = "032"
}