Não informado. (1951). FAO Fertilizer Yearbook. Food and Agriculture Organization of the United Nations.
Chicago-Zitierstil (17. Ausg.)Não informado. FAO Fertilizer Yearbook. Rome: Food and Agriculture Organization of the United Nations, 1951.
MLA-Zitierstil (8. Ausg.)Não informado. FAO Fertilizer Yearbook. Food and Agriculture Organization of the United Nations, 1951.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.