* The Princess of the Silver Woods
* The Prince and the Poison Kiss
* The Fairy Queen's Key
* The Lost Crown of the Snow Queen
* The Witch's Apprentice
* The Wizard's Apprentice
* The Dragon's Apprentice
* The Elven Assassin's Apprentice
* The Dark Prince's Apprentice
Middle grade fiction
* The Enchanted Island
* The Land of the Lost Toys
* The Magic Tree House
* The Boxcar Children
* The Nancy Drew Mysteries
* The Hardy Boys Mysteries
* The Bobbsey Twins Mysteries
Nonfiction
* The History of the World
* The United States of America
* The World of Science
* The World of Animals
* The World of Plants
* The Human Body
* The Mind and the Brain
Autobiography
* My Life as an Author
* The Adventures of a Writer