Giambattista Amati, Claudio Carpineto, Giovanni Romano. Query Difficulty, Robustness, and Selective Application of Query Expansion. In Sharon McDonald, John Tait, editors, Advances in Information Retrieval, 26th European Conference on IR Research, ECIR 2004, Sunderland, UK, April 5-7, 2004, Proceedings. Volume 2997 of Lecture Notes in Computer Science, pages 127-137, Springer, 2004. [doi]
Abstract is missing.