@inproceedings{Otto1997c,
  series = {{LNCS}},
  year = {1997},
  volume = {1234},
  booktitle = {Proceedings of 4th Symposium on Logical Foundations of Computer
               Science, LFCS `97},
  publisher = {Springer-Verlag},
  author = {Otto, Martin},
  title = {Capturing bisimulation-invariant {P}time},
  pages = {294-305},
}