wow The Great Pyramid of Khufu. Retrieved April 12, 2005. "The Great Pyramid of Khufu is the largest pyramid in Egypt and was the tallest man-made structure in the world until 1888."
uwsp.edu
Michael Ritter (2003) [1]Archived 2008-05-11 at the Wayback Machine Dating the Pyramids. Retrieved April 13, 2005
web.archive.org
Michael Ritter (2003) [1]Archived 2008-05-11 at the Wayback Machine Dating the Pyramids. Retrieved April 13, 2005