Andrea Perego; Phil Archer. <a href="http://www.w3.org/TR/2007/WD-powder-voc-20070925"><cite>Protocol for Web Description Resources (POWDER): Web Description Resources (WDR) Vocabulary.</cite></a> 25 September 2007. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2007/WD-powder-voc-20070925">http://www.w3.org/TR/2007/WD-powder-voc-20070925</a>