It's better to read Li Yongle's book. The book with 660 questions is also good, but when doing 660 questions, you should sum up more and master the methods and skills of filling in the blanks and choosing. Personally, I think that the four textbooks for postgraduate entrance examination (the sixth edition of advanced mathematics of Tongji University, the second edition of Tsinghua University linear algebra edited by Ma Zhu, and the fourth edition of probability and mathematical statistics of Zhejiang University) are very important, and the textbooks are fundamental. It can be said that the topics of postgraduate entrance examination are all around textbooks. I am a math major who took the postgraduate entrance examination in 2009. At that time, there was a proof question about the mean value theorem, which was a theorem in the book, but many people couldn't answer it. Actually, the problem is not difficult. The key is whether we can make full use of the four textbooks. Suggestion: Read at least 2-3 textbooks, combined with Li Yongle's review book, you can do the second round of 660 questions and real questions, and the real questions for postgraduate entrance examination should be classified and repeated. I recommend the detailed explanation of the real questions published by Xi 'an Jiaotong University Press, which is better, and finally do some simulation questions. But the most important thing is the real questions and textbooks! Good luck!