Vida Dujmovic David Eppstein Matthew Suderman David R. Wood Drawings of planar graphs with few slopes and segments. 194-212 2007 38 Comput. Geom. 3 http://dx.doi.org/10.1016/j.comgeo.2006.09.002 db/journals/comgeo/comgeo38.html#DujmovicESW07