File:Cheyenne Mountain.jpgdoors, Cheyenne Mountain, Colorado. USAF photo. URL: https://www.cheyennemountain.af.mil archive copy at the Wayback Machine English Cheyenne Mountain Complex
File:Cheyenne Mountain Tunnels.jpgNORAD blast doors, Cheyenne Mountain, Colorado. USAF photo. URL: https://www.cheyennemountain.af.mil archive copy at the Wayback Machine English applies