Dimitris Chatzidimitriou, Jean-Florent Raymond, Ignasi Sau, Dimitrios M. Thilikos. An O(\log \mathrmOPT) O ( log OPT ) -Approximation for Covering/Packing Minor Models of θ _r θ r. In Laura Sanità, Martin Skutella, editors, Approximation and Online Algorithms - 13th International Workshop, WAOA 2015, Patras, Greece, September 17-18, 2015. Revised Selected Papers. Volume 9499 of Lecture Notes in Computer Science, pages 122-132, Springer, 2015. [doi]