Hello, Li Yongle Li Zhengyuan's book is the mainstream one for postgraduate entrance examination review, while Zhang Yu's book is used by fewer people. At present, Li Er's book has not been published. I have read two versions of Li Fan and Li Wang, and I feel that the difference is not very big, because it covers all the knowledge points in the review book, and these two books can also be done. However, I think many people use one from Li Yongle and Wang Shian. You can consider this. It turns out that Li Er's books are really good. They are all used for exams, but they are not published now (unfortunately). But it's better to use the latest books, my personal suggestion.

As for solving problems, Basic Pass 660 is a very good choice. The small questions in it are very clever and can be studied as big questions. After practicing to a certain extent, start to do real questions. I have done it many times (at least 6 or 7 times) and summarized it repeatedly (the real question is very important). Finally, Li Yongle's books in the sprint stage exceeded 135, which is also very good. The most important thing in postgraduate mathematics is to keep the problem-solving state. If you slack off for three days, your problem-solving level will drop.

I am a graduate student in the 12 exam, and I am one of them. If you need to know anything, you can ask me again. I hope I can help you.