http://www.mlit.go.jp/jidosha/kensatoroku/sikumi/sankou_05.htm
http://www.mlit.go.jp/jidosha/anzen/04relief/resourse/data/ryouritsuhyo.pdf
http://www.soumu.go.jp/main_sosiki/jichi_zeisei/czaisei/czaisei_seido/ichiran01_l.html
http://www.soumu.go.jp/main_sosiki/jichi_zeisei/czaisei/czaisei_seido/ichiran01_n.html