Christoph Ambühl Thomas Erlebach Matús Mihalák Marc Nunkesser Constant-Factor Approximation for Minimum-Weight (Connected) Dominating Sets in Unit Disk Graphs. 3-14 2006 conf/approx/2006 APPROX-RANDOM http://dx.doi.org/10.1007/11830924_3 db/conf/approx/approx2006.html#AmbuhlEMN06