@inproceedings{DawarOtto2005b,
  booktitle = {Proceedings of 20th {IEEE} Symposium on Logic in Computer Science
               {LICS}'05},
  year = {2005},
  author = {Dawar, Anuj and Otto, Martin},
  title = {Modal characterisation theorems over special classes of frames},
  pages = {21-30},
}