http://www.ikedahayato.com/index.php/archives/22534

http://www.mod.go.jp/j/approach/others/security/narisumashi.html

http://www.yuhikaku.co.jp/static/digital-book/index.html#hourei

http://news.goo.ne.jp/article/yomiuri/politics/20130404-567-OYT1T00545.html

http://www.fnn-news.com/news/headlines/articles/CONN00243450.html

http://www.nikkei.com/article/DGXNASDG0403M_U3A400C1CR8000/