@ARTICLE{gerven08qualitative,
  author = {van Gerven, M. A. J. and Lucas, P. J. F. and van der Weide, T. P.},
  title = {A Generic Qualitative Characterization of Independence of Causal Influence},
  journal = {International Journal of Approximate Reasoning},
  year = {2008},
  volume = {48},
  number = {1},
  pages = {214--136}
}