1. 〈http://discover1.mc.vanderbilt.edu/discover/public/causal_explorer/index.html〉.
2. 〈http://pages.cs.wisc.edu/∼dpage/kddcup2001/〉.
3. 〈http://people.csail.mit.edu/jrennie/20newsgroups/〉.
4. 〈http://www.causality.inf.ethz.ch/data/sido.html〉.
5. 〈http://www.csie.ntu.edu.tw/∼cjlin/libsvm/〉.