Harold N. Gabow An Ear Decomposition Approach to Approximating the Smallest 3-Edge Connected Spanning Subgraph of a Multigraph. 41-70 2004 18 SIAM J. Discrete Math. 1 http://dx.doi.org/10.1137/S0895480102405476 db/journals/siamdm/siamdm18.html#Gabow04