参考URL

http://www.asahi-net.or.jp/~ps8a-okzk/xml/xpath10/intro.html

http://www.atmarkit.co.jp/aig/01xml/xpath.html
http://www.doraneko.org/xml/xpath10/19991116/Overview.html

xpath2.0

http://www.xmlconsortium.org/wg/tech/WD-xpath20-20020816-Japan-without-Appendix.htm