Giambattista Amati Claudio Carpineto Giovanni Romano Advances in Information Retrieval, 29th European Conference on IR Research, ECIR 2007, Rome, Italy, April 2-5, 2007, Proceedings ECIR Lecture Notes in Computer Science 4425 Springer 2007 978-3-540-71494-1 db/conf/ecir/ecir2007.html