1. Owe, O., Schneider, G., Steffen, M.: Components, objects, and contracts. In: SAVCBS 2007, pp. 91–94. ACM Digital Library, Dubrovnik (2007)
2. van der Torre, L.: Contextual deontic logic: Normative agents, violations and independence. Ann. Math. Artif. Intell. 37(1-2), 33–63 (2003)
3. von Wright, G.H.: Deontic logic. Mind 60, 1–15 (1951)
4. Fischer, M.J., Ladner, R.E.: Propositional modal logic of programs. In: STOC 1977, pp. 286–294. ACM Press, New York (1977)
5. Harel, D., Kozen, D., Tiuryn, J.: Dynamic Logic. MIT Press, Cambridge (2000)