"Modern Information Retrieval" by Baeza-Yates / Ribeireo Neto a few years ago used to be a good standard work. I'm not sure though how well it's kept up in ter

"Modern Information Retrieval" by Baeza-Yates / Ribeireo Neto a few years ago used to be a good standard work. I'm not sure though how well it's kept up in terms of aspects like real-time search and graph search, both of which are fairly recent developments.