The Magic Tree House Research Guide 18-Book Set (American Revolution, Ancient Greece and the Olympics, Ancient Rome and Pompeii, Dinosaurs, Dolphins and Sharks, Knights and Castles, Mummies and Pyramids, Penguins and Antarctica,,The Magic Tree House Research Guide 18-Book Set (American Revolution, Ancient Greece and the Olympics, Ancient Rome and Pompeii, Dinosaurs, Dolphins and Sharks, Knights and Castles, Mummies and Pyramids, Penguins and Antarctica,,Magic Tree House Fact Trackers Series Complete 44 Book Collection Set: Mary Pope Osborne, Will Osborne, Natalie Pope Boyce: 9781338611250: Amazon.com: Books,Magic Tree House Research Guide Set: Mary Pope Osborne: Amazon.com: Books,Space (Magic Tree House Research Guide): Mary Pope Osborne, Will Osborne, Sal Murdocca: 9780375813566: Amazon.com: Books