Fisher, R. (1991). Heartland of a continent: America's plains and prairies. National Geographic Society.
芝加哥风格引文Fisher, Ron. Heartland of a Continent: America's Plains and Prairies. Washington, D.C.: National Geographic Society, 1991.
MLA引文Fisher, Ron. Heartland of a Continent: America's Plains and Prairies. National Geographic Society, 1991.
警告:这些引文格式不一定是100%准确.