[1]
[CITE[The Opera 7 and 8 DOCTYPE Switches]] <http://www.opera.com/docs/specs/doctype/>
([[名無しさん]])

[2]
[CITE[Welcome to the MSDN Library]] <http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnie60/html/cssenhancements.asp>
([[名無しさん]])


[3]
[CITE[Mozilla's DOCTYPE sniffing]] <http://www.mozilla.org/docs/web-developer/quirks/doctypes.html>
([[名無しさん]])