The best learning place for postgraduate entrance examination is school, and bookstores don't have that kind of atmosphere. The popular bookstore in Times Square is good, but the atmosphere of postgraduate entrance examination is not heavy, and leisure reading is ok. So you'd better go to school. There may be many undergraduates in other campuses. I suggest you go to the Wen Jing Library of Yang Da Normal University. You can enter freely without borrowing books. There are many graduate students in the reading room on the second or third floor, and age is not a problem.

And there is a lot of information, as well as tea.

I wish you success!