Lisa Greathouse & Stephanie Kuligowski 
Unsolved! Mysterious Places [PDF ebook] 

From Stonehenge to the Bermuda Triangle, there are many places on Earth that remain a mystery to scientists! Readers will discover these curious places–and more!–as they move through this fascinating nonfiction title. This mysterious book features detailed images, informational text, and stimulating facts and theories in conjunction with upper-level features, such as chapter format, a glossary of terms, and an index.