If you know the content of the e-book, you can find the relevant title by the title. The content of e-books was usually written by the author himself, so the title was usually related to the content. For example, if the theme of the e-book was a romance novel, the title might include words such as " romance "," love ", and " love story ". He could also find the relevant titles through the contents of the e-book. If the e-book contains an author's work, you can search for the author's name to find the relevant title. For example, if you knew that the author's name was Cao Xueqin, you could search for the related book title by searching for the name " Cao Xueqin." You can also use the search function of the e-book store to find the title. In the e-book store, one could use keywords to search for titles such as " Dream of the Red Chamber "," Cao Xue Village ", and so on. This way, he could find the title of the book that was related to the content.