출처 :
https://twitter.com/Alsace_class/status/820593314411880453
https://twitter.com/kleinenf/status/807640176558108672
http://www.mod.go.jp/j/approach/hyouka/seisaku/results/28/pdf/jizen_02_sankou.pdf
http://www.mod.go.jp/j/yosan/2017/gaisan.pdf
http://www.mod.go.jp/atla/soubi_system.html