APA (7th ed.) Citation

Allen, T. B. (2008). Declassified: 50 top-secret documents that changed history. National Geographic.

Chicago Style (17th ed.) Citation

Allen, Thomas B. Declassified: 50 Top-secret Documents That Changed History. Washington, D.C: National Geographic, 2008.

MLA (9th ed.) Citation

Allen, Thomas B. Declassified: 50 Top-secret Documents That Changed History. National Geographic, 2008.