APA (7th ed.) Citation

Friedman, T. L. (2005). The world is flat: A brief history of the twenty-first century. Penguin Books.

Chicago Style (17th ed.) Citation

Friedman, Thomas L. The World Is Flat: A Brief History of the Twenty-first Century. London: Penguin Books, 2005.

MLA (9th ed.) Citation

Friedman, Thomas L. The World Is Flat: A Brief History of the Twenty-first Century. Penguin Books, 2005.