Jurek Czyzowicz Stefan Dobrev H. González-Aguilar Rastislav Kralovic Evangelos Kranakis Jaroslav Opatrny Ladislav Stacho Jorge Urrutia Local 7-Coloring for Planar Subgraphs of Unit Disk Graphs. 170-181 2008 TAMC http://dx.doi.org/10.1007/978-3-540-79228-4_15 conf/tamc/2008 db/conf/tamc/tamc2008.html#CzyzowiczDGKKOSU08