Chris Lilley; Tantek &#199;elik; L. David Baron. <a href="http://www.w3.org/TR/2008/WD-css3-color-20080721"><cite>CSS Color Module Level 3.</cite></a> 21 July 2008. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2008/WD-css3-color-20080721">http://www.w3.org/TR/2008/WD-css3-color-20080721</a>