APA (7th ed.) Citation

Duffy. (2014). Double agent: The first hero of World War II and how the FBI outwitted and destroyed a Nazi spy ring. Scribner.

Chicago Style (17th ed.) Citation

Duffy. Double Agent: The First Hero of World War II and How the FBI Outwitted and Destroyed a Nazi Spy Ring. New York: Scribner, 2014.

MLA (8th ed.) Citation

Duffy. Double Agent: The First Hero of World War II and How the FBI Outwitted and Destroyed a Nazi Spy Ring. Scribner, 2014.