Cita APA (7th ed.)

Beals, C. (1939). American earth: The biography of a nation. Lippincott.

Cita Chicago (17th ed.)

Beals, Carleton. American Earth: The Biography of a Nation. Philadelphia: Lippincott, 1939.

Cita MLA (9th ed.)

Beals, Carleton. American Earth: The Biography of a Nation. Lippincott, 1939.