Kamal Jain Ion I. Mandoiu Vijay V. Vazirani David P. Williamson A primal-dual schema based approximation algorithm for the element connectivity problem. 1-15 2002 45 J. Algorithms 1 http://dx.doi.org/10.1016/S0196-6774(02)00222-5 db/journals/jal/jal45.html#JainMVW02