https://www.jiji.com/jc/article?k=000000821.000002360&g=prt

http://maga9.jp/morinaga170830/

https://mainichi.jp/articles/20170828/k00/00e/040/185000c

http://www.yuhikaku.co.jp/books/detail/9784641137356

http://www3.nhk.or.jp/news/html/20170831/k10011119911000.html