Cita APA (7th ed.)
Schopenhauer, A. The Fourfold Root of the Principle of Sufficient Reason. Open Court.
Cita Chicago (17th ed.)
Schopenhauer, Arthur. The Fourfold Root of the Principle of Sufficient Reason. La Salle, EUA: Open Court.
Cita MLA (9th ed.)
Schopenhauer, Arthur. The Fourfold Root of the Principle of Sufficient Reason. Open Court.
Atenció: Aquestes cites poden no estar 100% correctes.