@incollection{DuchierGardent01,
  author	= {Duchier, Denys and Gardent, Claire},
  editor	= {???},
  title		= {Tree descriptions, Constraints and Incrementality},
  booktitle	= {???},
  pages		= {???},
  publisher	= {Kluwer Academic Press},
  year		= {2001},
  address	= {???}
}