Dick Bulterman; et al. <a href="http://www.w3.org/TR/2005/REC-SMIL2-20051213"><cite>Synchronized Multimedia Integration Language (SMIL 2.1).</cite></a> 13 December 2005. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2005/REC-SMIL2-20051213">http://www.w3.org/TR/2005/REC-SMIL2-20051213</a>