Sea Monsters: A Nonfiction Companion to Magic Tree House Merlin Mission #11: Dark Day in the Deep Sea (Magic Tree House: Fact Trekker Book 17)

Sabertooths and the Ice Age: A Nonfiction Companion to Magic Tree House #7: Sunset of the Sabertooth (Magic Tree House (R) Fact Tracker)

Tsunamis and Other Natural Disasters: A Nonfiction Companion to Magic Tree House #28: High Tide in Hawaii (Magic Tree House (R) Fact Tracker)

Dinosaurs: A Nonfiction Companion to Magic Tree House #1: Dinosaurs Before Dark (Magic Tree House (R) Fact Tracker)

Ancient Rome and Pompeii: A Nonfiction Companion to Magic Tree House #13: Vacation Under the Volcano (Magic Tree House (R) Fact Tracker)

Rain Forests: A Nonfiction Companion to Magic Tree House #6: Afternoon on the Amazon (Magic Tree House (R) Fact Tracker)

Ninjas and Samurai: A Nonfiction Companion to Magic Tree House #5: Night of the Ninjas (Magic Tree House (R) Fact Tracker)

Ghosts: A Nonfiction Companion to Magic Tree House Merlin Mission #14: A Good Night for Ghosts (Magic Tree House (R) Fact Tracker)

Vikings: A Nonfiction Companion to Magic Tree House #15: Viking Ships at Sunrise (Magic Tree House (R) Fact Tracker)