@incollection{Otto2006,
  author = {Goranko, Valentin and Otto, Martin},
  publisher = {Elsevier},
  title = {Model Theory of Modal Logic},
  pages = {255-325},
  editor = {P. Blackburn and F. Wolter and J. van Benthem},
  year = {2006},
  booktitle = {Handbook of Modal Logic},
}