• [2] User Interface Enhancements (1999-09-16 05:07:02 +09:00 版) http://www.w3.org/TR/1999/WD-css3-userint-19990916#at-rule-preference
• [1] User Interface for CSS3 (2000-06-23 03:09:21 +09:00 版) http://www.w3.org/TR/2000/WD-css3-userint-20000216#at-rule-preference