S. Guha, R. Rastogi, и K. Shim. ICDE '99: Proceedings of the 15th International Conference on Data Engineering, стр. 512. Washington, DC, USA, IEEE Computer Society, (1999)
T. Zhang, R. Ramakrishnan, и M. Livny. SIGMOD '96: Proceedings of the 1996 ACM SIGMOD international conference on Management of data, стр. 103--114. New York, NY, USA, ACM, (1996)