APA

United States, . (1972). Employment and population changes: standard metropolitan statistical areas and central cities. [Washington: For sale by the Supt. of Docs., U.S. Govt. Print. Off.

Chicago

United States, . 1972. Employment and population changes: standard metropolitan statistical areas and central cities. [Washington: For sale by the Supt. of Docs., U.S. Govt. Print. Off.

Harvard

United States, . (1972). Employment and population changes: standard metropolitan statistical areas and central cities. [Washington: For sale by the Supt. of Docs., U.S. Govt. Print. Off.

MLA

United States, . Employment and population changes: standard metropolitan statistical areas and central cities. [Washington: For sale by the Supt. of Docs., U.S. Govt. Print. Off. 1972.