Jean Cardinal Sébastien Collette Ferran Hurtado Stefan Langerman Belén Palop Optimal location of transportation devices. 219-229 2008 41 Comput. Geom. 3 https://doi.org/10.1016/j.comgeo.2008.01.001 db/journals/comgeo/comgeo41.html#CardinalCHLP08