@Article{	  Hertrampf96mst,
  title		= "On Balanced vs. Unbalanced Computation Trees",
  journal	= "Math. Systems Theory",
  year		= "1996",
  volume	= "29",
  number	= "4",
  pages		= "411--421",
  issn		= "0025-5661",
  doi		= "10.1007/BF01192696",
  author	= "Hertrampf, U. and Vollmer, H. and Wagner, K. W."
}