[1] [CITE[Document Structure – SVG 1.1 (Second Edition)]]
( ([TIME[2011-08-10 12:35:27 +09:00]] 版))
<http://www.w3.org/TR/2011/REC-SVG11-20110816/struct.html#InterfaceGetSVGDocument>

[2] [CITE@en[829872 – Consider returning null from contentDocument getters when the caller does not subsume the document]]
( ([TIME[2013-11-13 20:41:52 +09:00]] 版))
<https://bugzilla.mozilla.org/show_bug.cgi?id=829872>