David A. Bader Shiva Kintali Kamesh Madduri Milena Mihail Approximating Betweenness Centrality. 124-137 2007 conf/waw/2007 WAW http://dx.doi.org/10.1007/978-3-540-77004-6_10 db/conf/waw/waw2007.html#BaderKMM07