As part of a major rebrand programme, HarperCollins is relaunching Dr. Seuss's best-selling books. In response to consumer demand, bright new cover designs incorporate much-needed guidance on reading levels. The standard paperbacks divide into three reading strands - Blue Back Books for parents to share with young children, Green Back Books for budding readers to tackle on their own, and Yellow Back Books for older, more fluent readers to enjoy. This is a Green Back book.