[1] Web Forms 2.0 (2009-01-05 20:07:15 +09:00 版) <http://www.whatwg.org/specs/web-forms/current-work/#selectedindex>

[2] [CITE@@en[Web Applications 1.0 r5439 HTMLOptionsCollection.selectedItemFixing http://www.w3.org/Bugs/Public/show_bug.cgi?id=10184]] ( (2010-09-08 14:16:00 +09:00 版)) <http://html5.org/tools/web-apps-tracker?from=5438&to=5439>