[1] OAuth Echo | Twitter Developers (2015-03-05 11:41:22 +09:00 版) <https://dev.twitter.com/oauth/echo>

[2] OAuth Echo - Identity Verification Delegation (Draft (2015-03-05 11:45:38 +09:00 版) <http://ja.scribd.com/doc/26707268/OAuth-Echo-Identity-Veri%EF%AC%81cation-Delegation-Draft>

[3] TwitPic Developers - API Documentation (2015-03-05 11:49:49 +09:00 版) <http://web.archive.org/web/20140701155155/http://dev.twitpic.com/docs/>

[4] OAuth Echoを調べたのでメモ - BangBlog (2015-03-13 09:12:18 +09:00 版) <http://bang.hateblo.jp/entry/20101127/1290883965>