These books, answering questions from all subjects and all about the things in the world, living and non-living, existing and non-existing some of the questions are, What is Biology? What is a toucan? What is memory? What is genius? Why do we have grammar? Who made the first doll? What was a unicorn? Does the giraffe have a voice? What is the riddle of the Nile? What is a weevil? What causes dandruff? How did skiing begin? How did income tax start? Why do we have Christmas trees? What are phagocytes? What are aborigines? Is all rice white? Why did Rome fall? What is the 17-year locust? Do hyenas really laugh? How many kinds of oranges are there? Is the tomato a fruit or vegetable? What is the Rosetta stone? Who was bolivar? What is the Narwhal? What are dies and moulds? Why is fire hot? Unavoidable books for students who wants to know and to have a glance over the treasure of knowledge hidden and unknown.