@article{palla2007quantitative,
  title={Quantitative social group dynamics on a large scale},
  author={Palla, Gergely and Barab{\'a}si, Albert-L{\'a}szl{\'o} and Vicsek, Tam{\'a}s},
  journal={communities},
  volume={5},
  pages={23},
  year={2007}
}