[1] [CITE@en-gb[HTTP Status Codes]]
([[Dan McCormick]] 著, [TIME[2011-10-07 11:42:55 +09:00]] 版)
<http://www.mccormickfamily.com/become-an-author/56-http-status-codes#509>

[2] [CITE@en[List of HTTP status codes - Wikipedia, the free encyclopedia]]
( ([TIME[2012-02-16 13:47:30 +09:00]] 版))
<http://en.wikipedia.org/wiki/List_of_HTTP_status_codes>