10 books • 1 series
Mathematics (Ripley's Believe It or Not! Mind Teasers)
Hours, Days, and Years (Ripley's Believe It or Not! Mind Teasers)
Far and Wide (Ripley's Believe It or Not! Mind Teasers)
Great Sports Performance
The Human Body
Physical World (Ripley's Believe It or Not! Mind Teasers)
Getting There (Ripley's Believe It or Not! Mind Teasers)
Fun and Games
Ripleys Believ
Ripley's Believe It or Not!