http://www.nikkei.com/article/DGXLASGM04H0I_W5A400C1EAF000/?dg=1

http://gendai.ismedia.jp/articles/-/42803 http://gendai.ismedia.jp/articles/-/42804

http://www.chusho.meti.go.jp/zaimu/shoukei/2015/150407hikitugi.htm

http://headlines.yahoo.co.jp/hl?a=20150407-00000015-kyt-l26

http://news.goo.ne.jp/article/jiji/politics/jiji-150407X398.html