The Vulture Island Adventure Series

The Kingdom of Trung Trung Karmo: 5 (Vulture Island Adventure Series), by Judy Brulo
The Mystery of the Never-Ending Universe: Another Gripping Vulture Island Adventure: 2 (Vulture Island Trilogy), by Judy Brulo
Leave No Footprints: The Never-Ending Universe Revisited: 6 (Vulture Island Adventure Series), by Judy Brulo
The Buried City: A Tale of Two Time Zones: 4 (The Vulture Island Trilogy), by Judy Brulo
Swords in the Sky: 3 (Vulture Island Trilogy), by Judy Brulo
Revenge of the Servants of the Gods: 1 (The Vulture Island Trilogy), by Judy Brulo