Cita APA (7th ed.)
Horn, S. (2002). Law of gravity. HarperTorch.
Cita Chicago (17th ed.)
Horn, Stephen. Law of Gravity. New York: HarperTorch, 2002.
Cita MLA (9th ed.)
Horn, Stephen. Law of Gravity. HarperTorch, 2002.
Atenció: Aquestes cites poden no estar 100% correctes.