@inproceedings{viswanath-2009-activity,
  author = {Bimal Viswanath and Alan Mislove and Meeyoung Cha and Krishna P. Gummadi},
  title = {On the Evolution of User Interaction in Facebook}, 
  booktitle = {Proceedings of the 2nd ACM SIGCOMM Workshop on Social Networks (WOSN'09)},
  location = {Barcelona, Spain},
  month = {August},
  year = {2009}
}