APA-viite (7. p.)

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

Chicago-viite (17. p.)

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

MLA-viite (9. p.)

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