They began reporting, in fact, the best sellers from 20 different categories, such as " e-book fiction" and " combined print" – that is, paper and e-book nonfiction.

事实上，他们开始报告 20 个不同类别的畅销书，例如“电子书小说” 和“组合印刷” ——即纸质和电子书非小说类。