United States. Department of Agriculture. Economic Research Service. (1994). Agricultural resources and environmental indicators. The Service.
Cita Chicago (17th ed.)United States. Department of Agriculture. Economic Research Service. Agricultural Resources and Environmental Indicators. Washington, DC: The Service, 1994.
Cita MLA (9th ed.)United States. Department of Agriculture. Economic Research Service. Agricultural Resources and Environmental Indicators. The Service, 1994.
Atenció: Aquestes cites poden no estar 100% correctes.