David Hirtle; et al. <a href="http://www.w3.org/TR/2008/WD-rif-ucr-20081218"><cite>RIF Use Cases and Requirements.</cite></a> 18 December 2008. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2008/WD-rif-ucr-20081218">http://www.w3.org/TR/2008/WD-rif-ucr-20081218</a>