APA

United States. Department of Commerce, . (1971). Classified index of industries and occupations. Washington: D. C. Government Printing Office.

Chicago

United States. Department of Commerce, . 1971. Classified index of industries and occupations. Washington: D. C. Government Printing Office.

Harvard

United States. Department of Commerce, . (1971). Classified index of industries and occupations. Washington: D. C. Government Printing Office.

MLA

United States. Department of Commerce, . Classified index of industries and occupations. Washington: D. C. Government Printing Office. 1971.