@inproceedings{GraedelHirschOtto2000,
  title = {Back and forth between guarded and modal logics},
  pages = {217-228},
  author = {Gr{\"a}del, Erich and Hirsch, Colin and Otto, Martin},
  booktitle = {Proceedings of 15th {IEEE} Symposium on Logic in Computer Science
               {LICS}'00},
  year = {2000},
}