@Article{	  Wich01mfcs,
  author	= "Wich, Klaus",
  title		= "Characterization of Context-{F}ree Languages with
		  Polynomially Bounded Ambiguity",
  year		= "2001",
  volume	= "2136",
  pages		= "703--714",
  publisher	= "Springer",
  address	= "Berlin",
  series	= "Lecture Notes in Computer Science",
  booktitle	= "26th International Symposium, MFCS 2001 Marianske Lazne,
		  Czech Republic, August 27-31, 2001 Proceedings",
  doi		= "10.1007/3-540-44683-4_61"
}