48 books • 17 series
Project X CODE Extra: Purple Book Band, Oxford Level 8: Wonders of the World: See the Sights! (Project X CODE Extra)
Project X CODE Extra: Purple Book Band, Oxford Level 8: Pyramid Peril: Pyramid Secrets (Project X CODE Extra)
Dark Blue Book Band, Oxford Level 15: Top Secret: The Spy's Secret Handbook (Project X Origins)