Cita APA (7th ed.)

Ullmann, W. (1965). A history of political thought: The middle ages. Penguin.

Cita Chicago (17th ed.)

Ullmann, Walter. A History of Political Thought: The Middle Ages. Harmondsworth: Penguin, 1965.

Cita MLA (9th ed.)

Ullmann, Walter. A History of Political Thought: The Middle Ages. Penguin, 1965.