[1] DOM Standard ( (2014-06-23 14:49:32 +09:00 版)) <http://dom.spec.whatwg.org/#concept-traversal-whattoshow>

[2] DOM Standard ( (2014-06-23 14:49:32 +09:00 版)) <http://dom.spec.whatwg.org/#dom-nodeiterator-whattoshow>

[3] DOM Standard ( (2014-06-23 14:49:32 +09:00 版)) <http://dom.spec.whatwg.org/#dom-treewalker-whattoshow>