https://www.nikkei.com/article/DGKKZO30440750T10C18A5TJC000/

https://mainichi.jp/articles/20180514/ddm/001/040/179000c

https://www.nikkei.com/article/DGKKZO3037022011052018TCJ000/

http://www.nenkin.go.jp/service/jukyu/shougainenkin/ninteikijun/20140604.html

http://www.courts.go.jp/app/files/hanrei_jp/735/087735_hanrei.pdf