@InProceedings{	  wic2000dlt,
  author	= "Klaus Wich",
  title		= "Exponential Ambiguity of Context-free Grammars",
  booktitle	= "Proc. 4th International Conference on Developments in
		  Language Theory, July 1999",
  publisher	= "World Scientific, Singapore",
  editor	= "G. Rozenberg and W. {\relax Th}omas",
  pages		= "125--138",
  year		= "2000"
}