Marshak, S., & Prothero, D. R. Earth: Portrait of a planet.
Cita Chicago (17th ed.)Marshak, Stephen, i Donald R. Prothero. Earth: Portrait of a Planet.
Cita MLA (8th ed.)Marshak, Stephen, i Donald R. Prothero. Earth: Portrait of a Planet.
Atenció: Aquestes cites poden no estar 100% correctes.