Não informado. (2004). Ers. U.S. Department of Agriculture, Economic Research Service.
Chicago-Zitierstil (17. Ausg.)Não informado. Ers. Washington: U.S. Department of Agriculture, Economic Research Service, 2004.
MLA-Zitierstil (8. Ausg.)Não informado. Ers. U.S. Department of Agriculture, Economic Research Service, 2004.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.