1. Calardo, E., Rotolo, A.: Variants of multi-relational semantics for propositional non-normal modal logics. Journal of Applied Non-Classical Logics 24(4), 293–320 (2014)
2. Chellas, B.F.: Modal logic: an introduction. Cambridge university press (1980)
3. Donagan, A.: Consistency in rationalist moral systems. The Journal of Philosophy 81(6), 291–309 (1984)
4. Goble, L.: Preference semantics for deontic logic part i—simple models. Logique et Analyse 46(183–184), 383–418 (2003)
5. Goble, L.: Preference semantics for deontic logic part ii—multiplex models. Logique et Analyse 47(185–188), 335–363 (2004)