Nathalie Henry Anastasia Bezerianos Jean-Daniel Fekete Improving the Readability of Clustered Social Networks using Node Duplication. 1317-1324 2008 14 IEEE Trans. Vis. Comput. Graph. 6 http://doi.ieeecomputersociety.org/10.1109/TVCG.2008.141 db/journals/tvcg/tvcg14.html#HenryBF08