Cita APA (7a ed.)

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

Cita Chicago Style (17a ed.)

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

Cita MLA (9a ed.)

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