John Ellson, Emden R. Gansner, Eleftherios Koutsofios, Stephen C. North, Gordon Woodhull. Graphviz - Open Source Graph Drawing Tools. In Petra Mutzel, Michael Jünger, Sebastian Leipert, editors, Graph Drawing, 9th International Symposium, GD 2001 Vienna, Austria, September 23-26, 2001, Revised Papers. Volume 2265 of Lecture Notes in Computer Science, pages 483-484, Springer, 2001. [doi]