Kunihiko Sadakane Hiroshi Imai Kensuke Onishi Mary Inaba Fumihiko Takeuchi Keiko Imai Voronoi Diagrams by Divergences with Additive Weights. 403-404 1998 Symposium on Computational Geometry http://doi.acm.org/10.1145/276884.276929 db/conf/compgeom/compgeom98.html#SadakaneIOITI98