United States: Recommended Reading

For further study about United States, Martin Gray recommends the following books and travel guides:

Sacred Places of North America: 108 Destinations	Mysterious Ancient America: An Investigation into the Enigmas of America's Pre-History	Advanced Civilizations of Prehistoric America: The Lost Kingdoms of the Adena, Hopewell Mississippians, and Anasazi
Living the Sky: The Cosmos of the American Indian	The Moundbuilders: Ancient Peoples of Eastern North America