Silvio Ghilardi, Carsten Lutz, Frank Wolter, Michael Zakharyaschev. Conservative extensions in modal logic. In Guido Governatori, Ian M. Hodkinson, Yde Venema, editors, Advances in Modal Logic 6, papers from the sixth conference on Advances in Modal Logic, held in Noosa, Queensland, Australia, on 25-28 September 2006. pages 187-207, College Publications, 2006. [doi]
Abstract is missing.