HTML 5 Reference （页面存档备份，存于互联网档案馆）: "Although it is inspired by its SGML origins, in practice, it really only shares minor syntactic similarities." "As HTML5 is no longer formally based upon SGML, the DOCTYPE no longer serves this purpose, and thus no longer needs to refer to a DTD."
HTML5 DTD （页面存档备份，存于互联网档案馆）: "HTML5 is not SGML-based, and there will be no official DTD for it."
HTML 5 Reference （页面存档备份，存于互联网档案馆）: "Although it is inspired by its SGML origins, in practice, it really only shares minor syntactic similarities." "As HTML5 is no longer formally based upon SGML, the DOCTYPE no longer serves this purpose, and thus no longer needs to refer to a DTD."
Shannon Suetos. HTML5: Worth the Hype?. instantshift.com. 26 April 2010 [2012-10-21]. （原始内容存档于2011-03-07）.
Web Forms 2.0. 2009-01-05 [2014-02-11]. （原始内容存档于2014-02-09）. obsolescence notice
