http://dl.ndl.go.jp/view/download/digidepo_11045309_po_080506.pdf?contentNo=1

https://headlines.yahoo.co.jp/hl?a=20180221-00000008-kobenext-l28

https://mainichi.jp/articles/20180220/ddm/005/070/032000c

https://headlines.yahoo.co.jp/hl?a=20180221-00007420-bengocom-soci

https://headlines.yahoo.co.jp/hl?a=20180221-00000007-kyt-soci