@article{DBLP:journals/ai/DelgrandeSJ94,
  author = {Delgrande, James P. and Schaub, Torsten and Jackson, W. Ken},
  title = {Alternative Approaches to Default Logic},
  journal = {Artif. Intell.},
  volume = {70},
  number = {1-2},
  pages = {167--237},
  year = {1994}
}