6 books • 5 series
Investigating Ghosts (World's Greatest Mysteries)
Investigating the Bermuda Triangle (World's Greatest Mysteries)
12 Scientists Who Changed the World (Change Makers)
Investigating Seasons (Searchlight Books (TM) -- What Are Earth's Cycles?) (Searchlight Books - What Are Earth's Cycles?)
The Bermuda Triangle (Unsolved Mysteries)
Ghosts (Unsolved Mysteries)