Michael Johnston. <a href="http://www.w3.org/TR/2009/REC-emma-20090210"><cite>EMMA: Extensible MultiModal Annotation markup language.</cite></a> 10 February 2009. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2009/REC-emma-20090210">http://www.w3.org/TR/2009/REC-emma-20090210</a>