Ullmann, W. (1965). A history of political thought: The middle ages. Penguin.
Chicago Style (17. basım) AtıfUllmann, Walter. A History of Political Thought: The Middle Ages. Harmondsworth: Penguin, 1965.
MLA (9th ed.) AtıfUllmann, Walter. A History of Political Thought: The Middle Ages. Penguin, 1965.
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