Lofton Henderson; Benoit Bezaire. <a href="http://www.w3.org/TR/2009/WD-webcgm21-20090130"><cite>WebCGM 2.1.</cite></a> 30 January 2009. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2009/WD-webcgm21-20090130">http://www.w3.org/TR/2009/WD-webcgm21-20090130</a>