@Article{	  Wich02icalp,
  author	= "Wich, Klaus",
  title		= "Universal Inherence of Cycle-{F}ree Context-{F}ree
		  Ambiguity Functions",
  year		= "2002",
  volume	= "2380",
  pages		= "669--680",
  publisher	= "Springer",
  address	= "Berlin",
  series	= "Lecture Notes in Computer Science",
  booktitle	= "29th International Colloquium, ICALP 2002, Malaga, Spain,
		  July 8-13, 2002. Proceedings",
  doi		= "10.1007/3-540-45465-9_57"
}