G. Jeh, and J. Widom. Proceedings of the eighth ACM SIGKDD international conference on Knowledge discovery and data mining, page 538--543. New York, NY, USA, ACM, (2002)
R. Andersen, F. Chung, and K. Lang. Proceedings of the 47th Annual IEEE Symposium on Foundations of Computer Science, page 475--486. Washington, DC, USA, IEEE Computer Society, (2006)