Wendy Chisholm; Gregg Vanderheiden; Ian Jacobs. <a href="http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505"><cite>Web Content Accessibility Guidelines 1.0.</cite></a> 5 May 1999. W3C Recommendation. URL: <a href="http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505">http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505</a>