@InProceedings{	  Petersen96wccl,
  author	= "Petersen, Holger",
  title		= "The power of programs with restricted control structure",
  year		= "1996",
  volume	= "1",
  pages		= "56--58",
  publisher	= "Ernst-Moritz-Arndt-Universit{\"a}t",
  address	= "Greifswald",
  series	= "Preprint-Reihe Mathematik",
  booktitle	= "Preproceedings of WCCL'96"
}