Sang Won Bae Jae-Hoon Kim Kyung-Yong Chwa Optimal Construction of the City Voronoi Diagram. 95-117 2009 19 Int. J. Comput. Geometry Appl. 2 http://dx.doi.org/10.1142/S021819590900285X db/journals/ijcga/ijcga19.html#BaeKC09