S. Sen, F. Harper, A. LaPitz, and J. Riedl. GROUP '07: Proceedings of the 2007 international ACM conference on Supporting group work, page 361--370. New York, NY, USA, ACM, (2007)
A. Zubiaga, C. Körner, and M. Strohmaier. Proceedings of the 22nd ACM conference on Hypertext and hypermedia, page 93--102. New York, NY, USA, ACM, (2011)