@article{li2012mutual,
  title={Mutual or unrequited love: Identifying stable clusters in social networks with uni-and bi-directional links},
  author={Li, Y. and Zhang, Z.L. and Bao, J.},
  journal={WAW '12: Proceedings of the 9th Workshop on Algorithms and Models for the Web Graph},
  pages={113--125},
  year={2012},
  publisher={Springer}
}