The official information on XQuery [10] is comprehensive and
detailed, so much so in fact that it counts more than 170 printed pages. A more tutorial
approach can be found in the XQuery book by Wamlsley [61]
which gives good examples of use and tricks of the trade. Another excellent source of
examples are given in the XQuery Cookbook [54]. It also
gives examples of use of for the eXist
database and how XQuery can be
used with programming languages and environments.