Carl Sagan Quotes about Winter

"A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race". Book by Carl Sagan, p. 26, 1990.
Carl Sagan, Ann Druyan (2011). “Pale Blue Dot: A Vision of the Human Future in Space”, p.15, Ballantine Books
Carl Sagan (2011). “The Demon-Haunted World: Science as a Candle in the Dark”, p.400, Ballantine Books