Dyfyniad APA

Fisher, R. (1991). Heartland of a continent: America's plains and prairies. National Geographic Society.

Dyfyniad Arddull Chicago

Fisher, Ron. Heartland of a Continent: America's Plains and Prairies. Washington, D.C.: National Geographic Society, 1991.

Dyfyniad MLA

Fisher, Ron. Heartland of a Continent: America's Plains and Prairies. National Geographic Society, 1991.

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