@Article{	  adh03,
  author	= "Holger Austinat and Volker Diekert and Ulrich Hertrampf",
  journal	= "Theoretical Computer Science",
  pages		= "33--43",
  title		= "A Structural Property of Regular Frequency Computations ",
  volume	= "292",
  number	= "1",
  year		= "2003",
  doi		= "10.1016/S0304-3975(01)00213-4"
}