Brad Porter; et al. <a href="http://www.w3.org/TR/2004/REC-voicexml20-20040316"><cite>Voice Extensible Markup Language (VoiceXML) Version 2.0.</cite></a> 16 March 2004. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2004/REC-voicexml20-20040316">http://www.w3.org/TR/2004/REC-voicexml20-20040316</a>