Which is the best book to learn and understand XQuery?

Which is the best book to learn and understand XQuery for a beginner like me? Please note, I understand other XML technologies.

It would be really good if the book gives reasoning behind decisions. Strengths and weaknesses of XQuery. When to use and when not to use XQuery?

From stackoverflow $pageUsers[$entry.posts[0].author].name

• I like "XQuery" from O'Reilly.

  Another good one is "XQuery: The XML Query Language"

  From aku

• I have XQuery from the Experts, but I'm not sure if it is easy reading. I think XQuery is pretty complicated so there might not be an easy read on the subject.

  From Bryant

• The folks at W3Schools have some pretty good tutorials and resources for a variety of web technologies, you may want to start with their XQuery tutorial. That may give you a better understanding with which to evaluate what book suites your needs and learning style.

  From Joe Skora