Não informado. Philippine Journal of Soils. Department of Agriculture and Natural Resources.
Chicago-Zitierstil (17. Ausg.)Não informado. Philippine Journal of Soils. Manila: Department of Agriculture and Natural Resources.
MLA-Zitierstil (8. Ausg.)Não informado. Philippine Journal of Soils. Department of Agriculture and Natural Resources.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.