This is a book series consisting of three books. The concept of this book series is to open the door of dream. These books are for teenagers, so they are brighter colors. Because the three stories are all about the growth of three teenagers, the main elements of the book cover are three different teenagers with the tools helping achieve their dreams. One of the books is about an astronaut of NASA, so the main design elements are the rocket and the metal door. One is about a pilot, so the main design elements are airplanes and windows. One is a book about a hot air balloon, so the main design elements are a hot air balloon and the wooden door.