APA (7th ed.) Citation

Gilbert, M. (1998). A history of the twentieth century / Martin Gilbert. HarperCollins.

Chicago Style (17th ed.) Citation

Gilbert, Martin. A History of the Twentieth Century / Martin Gilbert. London: HarperCollins, 1998.

MLA (9th ed.) Citation

Gilbert, Martin. A History of the Twentieth Century / Martin Gilbert. HarperCollins, 1998.

Warning: These citations may not always be 100% accurate.