APA

United States, . (2019). Encouraging the next generation to visit national parks: hearing before the Subcommittee on National Parks of the Committee on Energy and Natural Resources, United States Senate, One Hundred Fifteenth Congress, first session, September 27, 2017. Washington: U.S. Government Publishing Office.

Chicago

United States, . 2019. Encouraging the next generation to visit national parks: hearing before the Subcommittee on National Parks of the Committee on Energy and Natural Resources, United States Senate, One Hundred Fifteenth Congress, first session, September 27, 2017. Washington: U.S. Government Publishing Office.

Harvard

United States, . (2019). Encouraging the next generation to visit national parks: hearing before the Subcommittee on National Parks of the Committee on Energy and Natural Resources, United States Senate, One Hundred Fifteenth Congress, first session, September 27, 2017. Washington: U.S. Government Publishing Office.

MLA

United States, . Encouraging the next generation to visit national parks: hearing before the Subcommittee on National Parks of the Committee on Energy and Natural Resources, United States Senate, One Hundred Fifteenth Congress, first session, September 27, 2017. Washington: U.S. Government Publishing Office. 2019.