Não informado. Philippine Journal of Soils. Department of Agriculture and Natural Resources.
Chicago-viite (17. p.)Não informado. Philippine Journal of Soils. Manila: Department of Agriculture and Natural Resources.
MLA-viite (8. p.)Não informado. Philippine Journal of Soils. Department of Agriculture and Natural Resources.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.