I suggest you go to Zhongyuan Road, opposite the East Gate of Zheng Da, where there is a shop with a 50% discount, and the quality of the book is very good, so it should be genuine. I often buy it there.

I suggest you go to the antique city to buy it. It's cheap. Generally speaking, you don't need to buy books, just buy some reading for half a month.

There are many other exercise papers on the internet, which can be downloaded and done. If the Internet is not convenient, you can also buy it at the east gate of Zheng Da University, which is also 50% off.