Imma Boada Narcís Coll Joan Antoni Sellarès Dynamically Maintaining a Hierarchical Planar Voronoi Diagram Approximation. 836-846 http://dx.doi.org/10.1007/3-540-44842-X_85 2003 conf/iccsa/2003-3 ICCSA (3) db/conf/iccsa/iccsa2003-3.html#BoadaCS03