Não informado. Philippine Journal of Soils. Department of Agriculture and Natural Resources.
Chicago-referens (17:e uppl.)Não informado. Philippine Journal of Soils. Manila: Department of Agriculture and Natural Resources.
MLA-referens (8:e uppl.)Não informado. Philippine Journal of Soils. Department of Agriculture and Natural Resources.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.