Full Citation:
Michael R. Fellows, Frances A. Rosamond, Udi Rotics, Stefan Szeider. Clique-width Minimization is NP-hard. Proceedings of STOC 2006; the 38th ACM Symposium on Theory of Computing, Seattle, Washington, USA, pages 354-362, 2006, ACM.
Stefan Szeider is a Professor at the Algorithms and Complexity Group.