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In this undated image released by The Penguin Press, "George F. Kennan: An American Life," by John Lewis Gaddis is shown. On Monday, April 16, 2012, Gaddis won the Pulitzer Prize for biography for "George F. Kennan: An American Life." (AP Photo/The Penguin Press)

In this undated image released by The Penguin Press, "George F. Kennan: An American Life," by John Lewis Gaddis is shown. On Monday, April 16, 2012, Gaddis won the Pulitzer Prize for biography for "George F. Kennan: An American Life." (AP Photo/The Penguin Press)

2012 Pulitzer Prize winners

Winners of the 2012 Pulitzer Prizes.