Dyfyniad APA

(2011). National geographic. Washington, DC: National Geographic Society.

Dyfyniad Arddull Chicago

National Geographic. Washington, DC: National Geographic Society, 2011.

Dyfyniad MLA

National Geographic. Washington, DC: National Geographic Society, 2011.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.