Mark Twain (2014). “Mark Twain on Common Sense: Timeless Advice and Words of Wisdom from America's Most-Revered Humorist”, p.37, Skyhorse Publishing, Inc.
"Ethan Hawke Talks THE PURGE, Making Genre Movies, What the Film Says about Society, Violence in the Media, the Rating System, and More". Interview with Christina Radish, collider.com. June 3, 2013.