@inproceedings{DBLP:conf/ecsqaru/Schaub93,
  author = {Schaub, Torsten},
  title = {Variations of Constrained Default Logic},
  booktitle = {{ECSQARU}},
  series = {Lecture Notes in Computer Science},
  volume = {747},
  pages = {310--317},
  publisher = {Springer},
  year = {1993}
}