Christina Lioma, Birger Larsen, Hinrich Schütze. User Perspectives on Query Difficulty. In Giambattista Amati, Fabio Crestani, editors, Advances in Information Retrieval Theory - Third International Conference, ICTIR 2011, Bertinoro, Italy, September 12-14, 2011. Proceedings. Volume 6931 of Lecture Notes in Computer Science, pages 3-14, Springer, 2011. [doi]
Abstract is missing.