Takashi Imamichi Yohei Arahori Jaeseong Gim Seok-Hee Hong Hiroshi Nagamochi Removing Node Overlaps Using Multi-sphere Scheme. 296-301 2008 Graph Drawing http://dx.doi.org/10.1007/978-3-642-00219-9_28 conf/gd/2008 db/conf/gd/gd2008.html#ImamichiAGHN08