APA (7th ed.) Citation

Clark, C. (2013). Sleepwalkers: How Europe went to war in 1914. Penguin Books.

Chicago Style (17th ed.) Citation

Clark, Christopher. Sleepwalkers: How Europe Went to War in 1914. London: Penguin Books, 2013.

MLA (9th ed.) Citation

Clark, Christopher. Sleepwalkers: How Europe Went to War in 1914. Penguin Books, 2013.