@INPROCEEDINGS{mps09,
  author = {A. Montanari and G. Puppis and P. Sala},
  title = {A Decidable Spatial Logic with Cone-shaped Cardinal Directions},
  booktitle = {Proceedings of the 18th {EACSL} Annual Conference on Computer Science Logic (CSL)},
  year = {2009},
  pages = {394-408},
  series = {LNCS},
  volume = {5771},
  publisher = {Springer}
}