http://www.head-t.com/2009/01/2009-01-07-01.html
http://www.atmarkit.co.jp/fcoding/articles/objc/05/objc05b.html
http://otake3.com/2009-08-16-1.html
http://blog.livedoor.jp/second_flush/archives/51140166.html
http://cocoadays.blogspot.com/2010/07/nsarray-indexofobjectidenticalto.html
http://iphone-tora.sakura.ne.jp/nsarray.html
http://goer.geo.jp/archives/51
http://www.atmarkit.co.jp/fcoding/articles/objc/04/objc04c.html
http://sarudeki.maiway.jp/forum/topic/103
あとちょっとなんだが、、、