Zoll, D. A. (1974). Twentieth century political philosophy. Prentice-Hall.
Cita Chicago (17th ed.)Zoll, Donald Atwell. Twentieth Century Political Philosophy. Englewood Cliffs, N. J: Prentice-Hall, 1974.
Cita MLA (9th ed.)Zoll, Donald Atwell. Twentieth Century Political Philosophy. Prentice-Hall, 1974.
Atenció: Aquestes cites poden no estar 100% correctes.