S. Mounir, N. Goharian, M. Mahoney, A. Salem, and O. Frieder. Proceedings of the Conference on Parallel and Distributed Techniques and Applications, Las Vegas NV. Alta-Vista, page 799--815. (1998)
C. Giles, K. Bollacker, and S. Lawrence. Proceedings of the Third ACM Conference on Digital Libraries, Pittsburgh, PA, USA, page 89--98. New York, NY, USA, ACM, (1998)