@Article{	  Hertrampf90tcs,
  title		= "Relations among MOD-classes",
  journal	= "Theoretical Computer Science",
  year		= "1990",
  volume	= "74",
  number	= "3",
  pages		= "325--328",
  publisher	= "Elsevier Science Publishers Ltd.",
  address	= "Essex, UK",
  issn		= "0304-3975",
  doi		= "10.1016/0304-3975(90)90081-R",
  author	= "Hertrampf, Ulrich"
}