"Sometimes Youthful Stupidity is a Better way to Find Happiness than Making Mature Choices" by Frank Schaeffer, www.huffingtonpost.com. September 11, 2014.
Samuel George Morton, George Combe (1839). “Crania Americana; Or, A Comparative View of the Skulls of Various Aboriginal Nations of North and South America: To which is Prefixed an Essay on the Varieties of the Human Species”, p.88, Philadelphia : J. Dobson ; London : Simpkin, Marshall