1. Buy on an authorized e-commerce platform. Authorized e-commerce platforms, such as Taobao, Tmall and JD.COM, usually have many merchants selling Ni's genuine books. When buying, you can check the reputation rating and user evaluation of the merchants, and choose the merchants with good reputation to buy.

2. Buy in a physical bookstore. Some physical bookstores may sell Ni's genuine books. For example, Xinhua Bookstore. When purchasing, you can check the qualification and reputation of the bookstore and the copyright information of the book to ensure that the purchased book is genuine.