APA (7th ed.) Citation

Keegan, J. (1994). Six armies in Normandy: From D-Day to the liberation of Paris. Penguin Books.

Chicago Style (17th ed.) Citation

Keegan, John. Six Armies in Normandy: From D-Day to the Liberation of Paris. New York: Penguin Books, 1994.

MLA (9th ed.) Citation

Keegan, John. Six Armies in Normandy: From D-Day to the Liberation of Paris. Penguin Books, 1994.