Arthur Barstow. <a href="http://www.w3.org/TR/2007/NOTE-dfaui-20070912"><cite>Declarative Formats for Applications and User Interfaces.</cite></a> 12 September 2007. W3C Note. URL: <a href="http://www.w3.org/TR/2007/NOTE-dfaui-20070912">http://www.w3.org/TR/2007/NOTE-dfaui-20070912</a>