MohammadAli Safari Mohammad R. Salavatipour A Constant Factor Approximation for Minimum <i>λ</i>-Edge-Connected <i>k</i>-Subgraph with Metric Costs. 1089-1102 2011 25 SIAM J. Discrete Math. 3 http://dx.doi.org/10.1137/080729918 db/journals/siamdm/siamdm25.html#SafariS11