[1] IRC logs: freenode / #whatwg / 20110412 ( (4/16/2011, 10:46:57 AM 版)) <http://krijnhoetmer.nl/irc-logs/whatwg/20110412>
[2] Web Applications 1.0 r7230 Mention that 'direction' is supposed to affect <input type=range> ( (8/9/2012, 4:45:00 PM 版)) <http://html5.org/tools/web-apps-tracker?from=7229&to=7230>
Google search: <input type=range>