Cita APA (7th ed.)

(2001). Yellowstone National Park / by David Petersen.

Cita Chicago (17th ed.)

Yellowstone National Park / by David Petersen. 2001.

Cita MLA (9th ed.)

Yellowstone National Park / by David Petersen. 2001.

Atenció: Aquestes cites poden no estar 100% correctes.