X. Zhang, B. Pielech, and E. Rundesnteiner. Proceedings of the 4th international workshop on Web information and data management, page 15--22. New York, NY, USA, ACM, (2002)
X. Zhang, K. Liu, L. Zou, X. Du, and S. Wang. Proceedings of the 12th international conference on Web-age information management, page 578--589. Berlin, Heidelberg, Springer-Verlag, (2011)