Gregg Vanderheiden; Wendy Chisholm; John Slatin. <a href="http://www.w3.org/TR/2006/NOTE-wcag2-req-20060425"><cite>Requirements for WCAG 2.0.</cite></a> 25 April 2006. W3C Note. URL: <a href="http://www.w3.org/TR/2006/NOTE-wcag2-req-20060425">http://www.w3.org/TR/2006/NOTE-wcag2-req-20060425</a>