A book for learners; a study book or textbook/workbook designed to help study a subject (e.g., language study books).
日本語の学習書を買って毎日30分勉強している。
I bought a Japanese study book and study for 30 minutes every day.
この学習書は文法の説明がとてもわかりやすい。
This study book explains grammar very clearly.
初級者向けの学習書には例文と練習問題が多く載っている。
Beginner study books often contain many example sentences and practice exercises.