http://news.goo.ne.jp/article/sankei/business/sankei-wst1512240078.html

http://m.jp.wsj.com/articles/JJ11986751506121504776318646122891170141785?mobile=y

http://www.asahi.com/articles/ASHDQ3RWRHDQUTIL01K.html

http://mainichi.jp/articles/20151225/k00/00m/040/140000c

http://www.sankei.com/affairs/news/151224/afr1512240017-n1.html