United States of America. Department of Commerce. Bureau of the Census. Demographic estimates for countries with a population of 10 million of more: 1981. Bureau of the Census.
Cita Chicago Style (17a ed.)United States of America. Department of Commerce. Bureau of the Census. Demographic Estimates for Countries with a Population of 10 Million of More: 1981. Washington: Bureau of the Census.
Cita MLA (9a ed.)United States of America. Department of Commerce. Bureau of the Census. Demographic Estimates for Countries with a Population of 10 Million of More: 1981. Bureau of the Census.
Precaución: Estas citas no son 100% exactas.