Warning - the bibtex entry below may be invalid: 
Missing 'publisher field' 
@book{adaptivewebsites,
  author = "J. D. Velasquez and V. Palade",
  title = "Adaptive Web Sites: A Knowledge Extraction from Web Data Approach",
  url = "http://www.amazon.com/Adaptive-Web-Sites-Intelligence-Applications/dp/1586038311/ref=sr_1_1?ie=UTF8&s=books&qid=1204466755&sr=8-1",
  year = "2008",
}