5J.-J.Ch. Meyer,W. van der Hoek. Epistemic Logic for Computer Science and Artificial Intelligence. Cambridge: Cambridge University Press, 1995.
6J. Lang, L. van der Torre, E. Weydert. Hidden Uncertainty in the Logical Representation of Desires. Proceedings of the 18th Interna- tional Joint Conference on Artificial Intelligence, 2003:189-231.