Chandra Chekuri Nitish Korula A Graph Reduction Step Preserving Element-Connectivity and Applications. 254-265 2009 ICALP (1) http://dx.doi.org/10.1007/978-3-642-02927-1_22 conf/icalp/2009-1 db/conf/icalp/icalp2009-1.html#ChekuriK09