D. Eastlake 3rd. <a href="http://www.ietf.org/rfc/rfc4051.txt"><cite>Additional XML Security Uniform Resource Identifiers</cite></a>. RFC 4051 April 2005. URL: <a href="http://www.ietf.org/rfc/rfc4051.txt">http://www.ietf.org/rfc/rfc4051.txt</a>