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Adamaszek, A., Blin, G., & Popa, A. (2015). Approximation and Hardness Results for the Maximum Edges in Transitive Closure Problem. In J. Kratchovíl, M. Miller, & D. Froncek (Eds.), Combinatorial Algorithms (pp. 13-23). Berlin: Springer. doi:10.1007/978-3-319-19315-1_2.