Hazel Everett Daniel Lazard Sylvain Lazard Mohab Safey El Din The Voronoi Diagram of Three Lines. 94-130 2009 42 Discrete & Computational Geometry 1 http://dx.doi.org/10.1007/s00454-009-9173-3 db/journals/dcg/dcg42.html#EverettLLD09