If it can be found in the online bookstore of Xidan Book Building, there will also be physical bookstores. They all use one kind of stock. If you go to the bookstore information desk to look up books, you can make a reservation without urgent need. The staff will specifically ask for what you need next time you enter the book. When the book arrives at the bookstore, the staff will contact you by phone. Just pay with the receipt at the time of booking.