There has been data ("日本一わかりやすい 坂田アキラの 三角比・平面図形が面白いほどとける本 (坂田アキラの理系シリーズ)") available for this ISBN from the data sources that books-by-isbn.com uses, but not on the latest request on Mon Dec 23 21:53:21 2019, so the data displayed here has been removed .