@article{DBLP:journals/ci/DelgrandeS04,
  author = {Delgrande, James P. and Schaub, Torsten},
  title = {Reasoning with Sets of Defaults in Default Logic},
  journal = {Computational Intelligence},
  volume = {20},
  number = {1},
  pages = {56--88},
  year = {2004}
}