Oscar D. Andrade, David G. Novick. Expressing help at appropriate levels. In Henrique O Neill, Manuela Aparicio, Carlos J. Costa, Aristidis Protopsaltis, editors, Proceedings of the 26th Annual International Conference on Design of Communication, SIGDOC 2008, Lisbon, Portugal, September 22-24, 2008. pages 125-130, ACM, 2008. [doi]
Abstract is missing.