Robin Berjon; Doug Schepers. <a href="http://www.w3.org/TR/2008/REC-ElementTraversal-20081222"><cite>Element Traversal Specification.</cite></a> 22 December 2008. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2008/REC-ElementTraversal-20081222">http://www.w3.org/TR/2008/REC-ElementTraversal-20081222</a>