Ralph R. Swick; Henry S. Thompson. <a href="http://www.w3.org/TR/1999/NOTE-schema-arch-19991007"><cite>The Cambridge Communiqu&#233;.</cite></a> 7 October 1999. W3C Note. URL: <a href="http://www.w3.org/TR/1999/NOTE-schema-arch-19991007">http://www.w3.org/TR/1999/NOTE-schema-arch-19991007</a>