Most users were unable to explain how they decided whether a book was useful or not, but some said that it was difficult and they would have liked more description, and a couple said that they would have to go and look at the book in order to know for sure. One user said (in the post-search interview) that he had thought hard about which books would be useful and which would not. He said that the date was very significant: ``If you're looking at this class of books, the classical calculus: the pre-1960's stuff I'm not interested in. I'm looking for where you can see actual applications.'' He also said, ``You can tell by the title. For example, I hnow that if there's Econometrics in the title then it's not going to be useful ... cos it's going to be about (unintelligible) and I don't need to know that ... and I also don't want something that's very advanced. There was one that said `Volume 1: Introduction' and that was great.''