National Research Council (U.S.). Board on Agriculture. Committee on Conservation Needs and Opportunities. (1986). Soil conservation: Assessing the national resources inventory. National Academy Press.
Dyfyniad Arddull ChicagoNational Research Council (U.S.). Board on Agriculture. Committee on Conservation Needs and Opportunities. Soil Conservation: Assessing the National Resources Inventory. Washington, D.C.: National Academy Press, 1986.
Dyfyniad MLANational Research Council (U.S.). Board on Agriculture. Committee on Conservation Needs and Opportunities. Soil Conservation: Assessing the National Resources Inventory. National Academy Press, 1986.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.