[1] CSS Conditional Rules Module Level 3 ( ( 版)) <http://www.w3.org/TR/2012/WD-css3-conditional-20120911/>
[2] Conditional Group Rules draft (better name needed) ( (L. David Baron 著, 版)) <http://lists.w3.org/Archives/Public/www-archive/2011Jun/0002.html>
[3] per-site user stylesheet rules ( (L. David Baron 著, 版)) <http://lists.w3.org/Archives/Public/www-style/2004Aug/0135>
[4] CSS Conditional Rules Module Level 3 ( ( 版)) <http://dev.w3.org/csswg/css-conditional/>