Artur Czumaj Jurek Czyzowicz Leszek Gasieniec Jesper Jansson Andrzej Lingas Pawel Zylinski Approximation Algorithms for Buy-at-Bulk Geometric Network Design. 168-180 2009 WADS http://dx.doi.org/10.1007/978-3-642-03367-4_15 conf/wads/2009 db/conf/wads/wads2009.html#CzumajCGJLZ09