E. Isaac Sparling, Shilad Sen. Rating: how difficult is it?. In Bamshad Mobasher, Robin D. Burke, Dietmar Jannach, Gediminas Adomavicius, editors, Proceedings of the 2011 ACM Conference on Recommender Systems, RecSys 2011, Chicago, IL, USA, October 23-27, 2011. pages 149-156, ACM, 2011. [doi]
Abstract is missing.