Science and Security Board Bulletin of the Atomic Scientists (August 9, 2011). "It is two and a half minutes to midnight"(PDF). Bulletin of the Atomic Scientists. Archived from the original(PDF) on January 26, 2017. Retrieved January 26, 2017.
Science and Security Board Bulletin of the Atomic Scientists (August 9, 2011). "It is two and a half minutes to midnight"(PDF). Bulletin of the Atomic Scientists. Archived from the original(PDF) on January 26, 2017. Retrieved January 26, 2017.