I think the textbook of Harbin Institute of Technology, Theoretical Mechanics, is good, because it is so good that it was borrowed by others that the author can't remember it. The publishing house is a higher education publishing house, and I use the third edition. As far as I know, the fourth edition has not yet come out, and the third edition is relatively mature. Textbooks are more detailed and self-study is better. The cover of this book is blue.