@inproceedings{shirali2009hard,
  author    = {Shirali-Shahreza, S. and Shirali-Shahreza, M.},
  title     = {Hard Graph Problems for Fighting with Spammers},
  booktitle = {Proceedings of the Second International Workshop on Knowledge Discovery and Data Mining (WKDD 2009)},
  address   = {Moscow, Russia},
  month     = jan,
  year      = {2009},
  pages     = {432--435},
}