Jean-Daniel Boissonnat Micha Sharir Boaz Tagansky Mariette Yvinec Voronoi Diagrams in Higher Dimensions under Certain Polyhedral Distance Functions. 79-88 1995 Symposium on Computational Geometry http://doi.acm.org/10.1145/220279.220288 db/conf/compgeom/compgeom95.html#BoissonnatSTY95