U.S. Bureau of the Census. (1981). Demographic estimates for countries with a population of 10 million or more: 1981. U.S. Government Printing Office.
Chicago-viite (17. p.)U.S. Bureau of the Census. Demographic Estimates for Countries with a Population of 10 Million or More: 1981. Washington, D.C: U.S. Government Printing Office, 1981.
MLA-viite (9. p.)U.S. Bureau of the Census. Demographic Estimates for Countries with a Population of 10 Million or More: 1981. U.S. Government Printing Office, 1981.
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