APA

United States, . (1993). Selected characteristics of occupations defined in the revised Dictionary of occupational titles. Pittsburgh, PA: U.S. Government Printing Office.

Chicago

United States, . 1993. Selected characteristics of occupations defined in the revised Dictionary of occupational titles. Pittsburgh, PA: U.S. Government Printing Office.

Harvard

United States, . (1993). Selected characteristics of occupations defined in the revised Dictionary of occupational titles. Pittsburgh, PA: U.S. Government Printing Office.

MLA

United States, . Selected characteristics of occupations defined in the revised Dictionary of occupational titles. Pittsburgh, PA: U.S. Government Printing Office. 1993.