The New Encyclopedia Britannica: Micropaedia, Location unknown, 04/02/2017. https://www.rawpixel.com/image/6113734/photo-image-book-public-domain-freeFree Image from public domain licenseFree man sitting on cliff watching mountain view photo, public domain travel CC0 image. https://www.rawpixel.com/image/5901855/photo-image-public-domain-mountain-freeFree Image from public domain license