They’re ancient and modern. They’re lost and found. What are they? History mysteries, of course! Get ready to crack the cases and the real history info wide open. You might need your time machine for this one.

They’re multiplied and divided. They’re spectacular and average. What are they? Math mysteries, of course! Get ready to crack the cases and the real math info wide open. You might need your abacus for this one.

They’re furry and funny. They’re tracked and tricky. What are they? Animal mysteries, of course! Get ready to crack the cases and the real animal info wide open. You might need your camouflage for this one.

They’re explosive and invisible. They’re extinct and never ending. What are they? Science mysteries, of course! Get ready to crack the cases and the real science info wide open. You might need your goggles for this one.

"Nonfiction history information is presented as mysteries for readers to solve. With the turn of a page, readers learn how to solve the true history mystery"--Provided by publisher.

Popular Mechanics inspires, instructs and influences readers to help them master the modern world. Whether it’s practical DIY home-improvement tips, gadgets and digital technology, information on the newest cars or the latest breakthroughs in science -- PM is the ultimate guide to our high-tech lifestyle.

Popular Science gives our readers the information and tools to improve their technology and their world. The core belief that Popular Science and our readers share: The future is going to be better, and science and technology are the driving forces that will help make it better.

The Advocate is a lesbian, gay, bisexual, transgender (LGBT) monthly newsmagazine. Established in 1967, it is the oldest continuing LGBT publication in the United States.

This Combo Collection (Set of 4 Books) includes All-time Bestseller Books. This anthology contains: The Adventure of the Devil's Foot The Adventure of the Cardboard Box The Adventure of Wisteria Lodge The Adventure of the Dying Detective