1. https://snap.stanford.edu/data/. https://snap.stanford.edu/data/.
2. http://research.microsoft.com/en-us/people/weic/graphdata.zip. http://research.microsoft.com/en-us/people/weic/graphdata.zip.
3. http://an.kaist.ac.kr/traces/WWW2010.html. http://an.kaist.ac.kr/traces/WWW2010.html.