Sailing in the Ocean of Art, edited by Zhou Zhiyu (Director of Basic Department of School of Design, Central Academy of Fine Arts), Shanxi People's Publishing House.
2. From Sketch to Design, edited by Wang Zhongyi (Basic Teaching and Research Section of China Academy of Fine Arts) and Xu Jiang (Dean of China Academy of Fine Arts), published by China Academy of Fine Arts.
3. The teaching series Rational Sketch —— Sketch Expression of Modern Art Concepts, edited by Hu, Jilin Fine Arts Publishing House.
4. The teaching series of Urban Design College of Central Academy of Fine Arts "Continuation of Rationality —— Teaching and Thinking of Rural Sketch in Academy of Fine Arts" was compiled by Hu and edited by Jilin Fine Arts Publishing House.
The book I recommend to you may not be an easy-to-understand textbook, but it is definitely the top work of China's design sketch, which is easy to understand and may not be suitable for beginners.
It can help you to have a correct understanding of design sketch, enhance your horizons, and be of great help to your selection of teaching materials from the shallow to the deep in the future.