" He also created warning cards to insert in the questionable books. He wanted the cards to say, “This book is of the worst class that we can possibly keep in the library. We are sorry that you have not any better sense than to read it,” but he was persuaded to use a more restrained tone. The cards, shaped like bookmarks, said, “For Later and More Scientific Treatment of This Subject, Consult ______,” followed by a blank space for librarians to list better books on the topic. "

― Susan Orlean , The Library Book