Michael Baur Ulrik Brandes Jürgen Lerner Dorothea Wagner Group-Level Analysis and Visualization of Social Networks. 330-358 2009 Algorithmics of Large and Complex Networks http://dx.doi.org/10.1007/978-3-642-02094-0_16 conf/dfg/2009netw db/conf/dfg/netw2009.html#BaurBLW09