Não informado. (1980). Soil and water conservation news. U.S. Department of Agriculture, Soil Conservation Service.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Soil and Water Conservation News. Washington: U.S. Department of Agriculture, Soil Conservation Service, 1980.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Soil and Water Conservation News. U.S. Department of Agriculture, Soil Conservation Service, 1980.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.