Additional Resources for page 53

Web site: Plague: The Black Death, National Geographic

Web page: Black Death, History

Web page: Secrets of the Dead—Case File: Mystery of the Black Death, PBS 

Web page: World War I, History

Web site: The Great War, PBS

Web site: First World War.com

Web site: World War One, BBC - History

Web site: The World War I Document Archive, Brigham Young U Library

Web page: Great Chicago Fire, Chicago Historical Society

Web site: Great Chicago Fire & The Web of Memory

Video: Great Chicago Fire 1871, The Weather Channel

Web page: Impact Risk, NASA Near Earth Object Program

PDF: Evolution of Impact Probability for Potential Earth Impactors, JPL/Caltech

Web page: Russian Asteroid Explosion and Past Impactors Paint a Potentially Grim Future for Earth, Universe Today