Farooq, U.; Kannampallil, T. G.; Song, Y.; Ganoe, C. H.; Carroll, J. M. & Giles, L. (2007), Evaluating tagging behavior in social bookmarking systems: metrics and design heuristics, in 'GROUP '07: Proceedings of the 2007 international ACM conference on Conference on supporting group work' , ACM, New York, NY, USA , pp. 351--360 .