@article{DBLP:journals/tcs/BesnardS00,
  author = {Besnard, Philippe and Schaub, Torsten},
  title = {What is a (non-constructive) non-monotone logical system?},
  journal = {Theor. Comput. Sci.},
  volume = {238},
  number = {1-2},
  pages = {489--494},
  year = {2000}
}