C. Papadimitriou. Proceedings of the 24th International Colloquium on Automata,
Languages, and Programming (ICALP 1997), volume 1256 of Lecture Notes in Computer Science, page 2--6. Springer, (1997)
C. Papadimitriou, and M. Yannakakis. Proceedings of the 10th Annual ACM Symposium on Principles of Distributed Computing, page 61--64. Montéal, Québec, Canada, ACM Press, (August 1991)
C. Daskalakis, P. Goldberg, and C. Papadimitriou. STOC '06: Proceedings of the thirty-eighth annual ACM symposium on Theory of computing, page 71--78. New York, NY, USA, ACM, (2006)