APA

United States, . (1973). The Administration's proposal for relaxation of air pollution standards: Hearing, Ninety-third Congress, first session. Washington: U.S. Govt. Print. Off.

Chicago

United States, . 1973. The Administration's proposal for relaxation of air pollution standards: Hearing, Ninety-third Congress, first session. Washington: U.S. Govt. Print. Off.

Harvard

United States, . (1973). The Administration's proposal for relaxation of air pollution standards: Hearing, Ninety-third Congress, first session. Washington: U.S. Govt. Print. Off.

MLA

United States, . The Administration's proposal for relaxation of air pollution standards: Hearing, Ninety-third Congress, first session. Washington: U.S. Govt. Print. Off. 1973.