@InProceedings{schwan02b,
  author =	 "T. Schaub and K. Wang",
  title =	 "Preferred well-founded semantics for logic programming by
alternating
                  fixpoints: Preliminary Report",
  booktitle =	 "Proceedings of the Workshop on Nonmonotonic Reasoning'2002",
  year =	 "2002",
  pages =	 "238-246"
}