@conference {875, title = {Social Comparisons to Motivate Contributions to an Online Community.}, booktitle = {Persuasive Technology}, year = {2007}, month = {26/04/2007}, address = {Palo Alto, CA}, author = {F. Harper and X. Li and Y. Chen and J. Konstan} } @conference {874, title = {Talk Amongst Yourselves: Inviting Users to Participate in Online Conversations.}, booktitle = {International Conference on Intelligent User Interfaces }, series = {Proceedings of the 12th international conference on Intelligent user interfaces}, year = {2007}, month = {28/01/2007}, pages = {62-71}, publisher = {ACM}, organization = {ACM}, address = {Honolulu, Hawaii}, isbn = {1-59593-481-2}, author = {F. Harper and D. Frankowski and Drenner, S. and Y. Ren and S. Kiesler and Terveen, L. and Kraut, R. and Riedl, J.} }