@InProceedings{AHW01,
  author =       {B.~Afshordel and Th.~Hillenbrand and 
                  Chr.~Weidenbach},
  title =        {First-Order Atom Definitions Extended},
  booktitle =    {Proceedings of the 8th International Conference
                  on Logic for Programming, Artificial
                  Intelligence and Reasoning},
  pages =        {309--319},
  year =         2001,
  editor =       {R.~Nieuwenhuis and A.~Voronkov},
  volume =       2250,
  series =       {LNAI},
  publisher =    {Springer-Verlag}
}