United States. Department of Agriculture. Economic Research Service. (1994). Agricultural resources and environmental indicators. The Service.
Chicago (17e ed.) BronvermeldingUnited States. Department of Agriculture. Economic Research Service. Agricultural Resources and Environmental Indicators. Washington, DC: The Service, 1994.
MLA (9e ed.) BronvermeldingUnited States. Department of Agriculture. Economic Research Service. Agricultural Resources and Environmental Indicators. The Service, 1994.