@Techreport{KoutsofiosNorth:2002,
author= "D. Dobkin and J. Ellson and E. Gansner and E. Koutsofios and 
S. North and G. Woodhull",
title= "Graphviz - Graph Drawing Programs",
institution= "AT\&T Research and Lucent Bell Labs", 
note         = "http://www.graphviz.org/",
year= "2002"}