Ilya Safro Dorit Ron Achi Brandt A Multilevel Algorithm for the Minimum 2-sum Problem. 237-258 2006 10 J. Graph Algorithms Appl. 2 http://jgaa.info/accepted/2006/SafroRonBrandt2006.10.2.pdf db/journals/jgaa/jgaa10.html#SafroRB06