Cita APA (7a ed.)

Roberts, J. M. (2000). The Penguin history of the twentieth century: The history of the world, 1901 to the present. Penguin Books.

Cita Chicago Style (17a ed.)

Roberts, John Morris. The Penguin History of the Twentieth Century: The History of the World, 1901 to the Present. London [etc.]: Penguin Books, 2000.

Cita MLA (9a ed.)

Roberts, John Morris. The Penguin History of the Twentieth Century: The History of the World, 1901 to the Present. Penguin Books, 2000.