How to Buy Banned Books in Beijing?

Zhang Yihe's new book, Past Stories of Peking Opera Stars, was banned, we are told by the South China Morning Post and International Herald Tribune.  But how do the propagandists ban a book?  That we are not told.  Do the big nannies sweep away the banned books and burn them, modelling themselves on Li Si, Emperor Qin's prime minister?

The reporter of Taiwan's United Daily visited Beijing bookshops after the "ban":

(In translation) Past Stories of Peking Opera Stars is displayed in prominent position in Beijing bookshops.  Some of them even put up advertisements to promote the book.  Mr Ai, manager of Beijing Wangfujing Bookstore, said Zhang's book was selling quite well.  Many people go to the help desk on the first floor to enquire about the book.  The staff are so familiar with the book that they can answer immediately.

... The manager said: "I have never heard that Past Stories of Peking Opera Stars was banned" ...

Open display of banned book (Beijing Wangfujing Bookstore, United Daily)

So what is a ban?  According to Zhang (English / Chinese), her first book The Past is Not Smoke was banned - i.e. the publisher could not print anymore after the existing copies sold out.

Source:
Zhang Yihe's Past Stories of Peking Opera Stars Big Hit in Beijing - United Daily (Chinese)