Mysteries of History: Mystery of the Nazca Lines
Special Reports: Vaccination Debate
Deadliest Diseases of All Time: Ebola
Mysteries of History: Mystery of the Roanoke Colonists
Climate Change: Examining the Facts
Special Reports: Ebola Outbreak
Mysteries of History: Mystery of the Sphinx
Secret Societies and Clubs in American History
The Central Intelligence Agency: An Encyclopedia of Covert Ops, Intelligence Gathering, and Spies
Investigating Atlantis and Other Lost Cities
Investigating Ghosts and the Spirit World
Investigating the Abominable Snowman and Other Legendary Beasts
Investigating Witches and Witchcraft
9/11 and the War on Terror: A Documentary and Reference Guide
Disasters and Tragic Events: An Encyclopedia of Catastrophes in American History