demarcation problem
https://source.unsplash.com/featured/?demarcation-problem#.png
/suto3/google.icondemarcation problem
/suto3/Google画像検索.icondemarcation problem
/suto3/Google定義検索.icon demarcation problem
/suto3/wikipedia.icondemarcation problem
/suto3/weblio.icon demarcation problem
/suto3/kotobank.icon demarcation problem
/suto3/jisho.icon demarcation problem