https://gigazine.net/news/20180403-tweetdelete/

http://www.chusho.meti.go.jp/zaimu/shoukei/2018/180403shoukei.htm

https://headlines.yahoo.co.jp/hl?a=20180402-00000009-asahik-soci

http://matimura.cocolog-nifty.com/matimulog/2018/04/jugement-0286.html

https://www.nishinippon.co.jp/nnp/national/article/406162/