@article{pollner2008centrality, title={Centrality properties of directed module members in social networks}, author={Pollner, P{\'e}ter and Palla, Gergely and {\'A}bel, D{\'a}niel and Vicsek, Andr{\'a}s and Farkas, Ill{\'e}s J and Der{\'e}nyi, Imre and Vicsek, Tam{\'a}s}, journal={Physica A: statistical Mechanics and its Applications}, volume={387}, number={19}, pages={4959--4966}, year={2008}, publisher={North-Holland} }