Ruffner, Kevin C., ed.

Corona: America’s First Satellite Program.

Washington, D.C.: Central Intelligence Agency, 1995.

Ryan, Cornelius.

The Last Battle.

New York: Simon & Schuster, 1966.

Sagan, Carl, et al.

Murmurs of Earth: The Voyager Interstellar Record.

New York: Random House, 1978.

Sagdeev, Roald Z.

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