@InProceedings{	  die85caas,
  author	= "Volker Diekert",
  address	= "Otzenhausen",
  booktitle	= "Combinatorial Algorithms in Algebraic Structures",
  editor	= "J. Avenhaus and others",
  pages		= "60--66",
  publisher	= "Fachbereich Informatik der Universit{\"a}t Kaiserslautern",
  title		= "A complete non-preperfect presentation of a context-free
		  monoid",
  year		= "1985"
}