Jiawei Zhang. Approximating the two-level facility location problem via a quasi-greedy approach. In J. Ian Munro, editor, Proceedings of the Fifteenth Annual ACM-SIAM Symposium on Discrete Algorithms, SODA 2004, New Orleans, Louisiana, USA, January 11-14, 2004. pages 808-817, SIAM, 2004. [doi]
Abstract is missing.