@article{1989-Falkenberg-ProcSem,
  author		= "Falkenberg, E.D. and Pols, R. van der and Weide, Th.P. van der",
  title			= "{Understanding process structure diagrams}",
  journal		= "Information Systems",
  number		= "4",
  volume		= "16",
  month			= "September",
  year			= "1991",
  research_group	= "iris",
  pages			= "417--428",
  class			= "Journal"
}