Modern algebra: There is a textbook written by Yang Zixu and a supporting study guide book, which can be referenced by Higher Education Press. He also wrote a problem set, but there were so many questions that he could hardly finish it.

Differential geometry: Chen has a book on differential geometry and a book on elementary differential geometry, with similar contents. The latter is simpler, mainly based on classical curve and surface theory, and there are also corresponding learning tutorials.

Complex Variable Function: The complex variable function written by Zhong Yuquan, and the corresponding study guidance book.

Ordinary Differential Equation: Ordinary Differential Equation written by Wang Gaoxiong and Zhou Zhiming, and the supporting counseling books are also well written.

Personally, I think it is enough to learn all the knowledge in the textbook in the future research work. Doing more questions is nothing more than taking exams, just like doing questions in the college entrance examination. It's no use after the exam. It is very important to learn a course and learn the way of thinking. Of course, exercise is essential. It should be said that it is not easy to understand all the questions after class. So I didn't mention the problem set (of course there are both). I think a reference book should be enough.