@incollection{Patten87,
  author	= {Patten, Terry and Ritchie, Graeme},
  editor	= {Kempen, Gerard},
  year		= {1987},
  title		= {A formal model of systemic grammar},
  booktitle	= {Natural Language Generation},
  publisher	= {Martinus Nijhof},
  address	= {Dordrecht}
}