@InCollection{Torre97TheManyFaces,
  Title                    = {The many faces of defeasibility in defeasible deontic logic},
  Author                   = {van der Torre, L. and Tan, Y},
  Booktitle                = {Defeasible Deontic Logic, volume 263 of Synthese Library},
  Publisher                = {Kluwer},
  Year                     = {1997},
  Editor                   = {Nute, D.},
  Pages                    = {79-121},

  Bdsk-url-1               = {http://icr.uni.lu/leonvandertorre/papers/ddl97.ps.Z},
  Date-modified            = {2011-12-20 17:12:38 +0100},
  Url                      = {http://icr.uni.lu/leonvandertorre/papers/ddl97.ps.Z}
}