脚注[脚注の使い方]^ “About the National Park Service”. National Park Service, U.S. Department of the Interior. 2020年7月4日閲覧。 “The National Park Service is a bureau of the U.S. Department of the Interior and is led by a Director nominated by the President and confirmed by the U.S. Senate.” ^ “政府閉鎖、アメリカの国立公園はゴミだらけに”. Business insider Japan (2019年1月7日). 2019年1月18日閲覧。