[1] [CITE@en[XHTML 1.0: The Extensible HyperText Markup Language (Third Edition)]] ([TIME[2008-11-22 03:45:46 +09:00]] 版) <http://www.w3.org/MarkUp/2008/ED-xhtml1-20081121/>

[2] [CITE@en[XHTML™ 1.0: The Extensible HyperText Markup Language (Third Edition)]] ([TIME[2009-05-06 18:26:25 +09:00]] 版) <http://www.w3.org/TR/2009/PER-xhtml1-20090507/>