@InProceedings{SVW05:entcs,
  author =   {A. Sokolova and Vink, E.P. de and H. Woracek},
  title =    {Weak bisimulation for action-type systems},
  booktitle =    {Proc.\ CTCS'04},
  pages =    {211--228},
  year =     2005,
  publisher =    {ENTCS~122}
}