@inproceedings{ han07a,
author = "J. Hansen, G. Pigozzi, and Leon van der Torre"
title =  "Ten philosophical problems in deontic logic",
editor = "G. Boella, L. van der Torre and H. Verhagen",
booktitle = "Normative Multi-Agent Systems. Dagstuhl Seminar Proceedings",
volume = "07122",
location = "Internationales Begegnungs- und Forschungszentrum fuer
            Informatik (IBFI), Schloss Dagstuhl, Germany",
year = "2007"}