Não informado. (1964). Soil and water. National Water and Soil Conservation Organization.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Soil and Water. Wellington: National Water and Soil Conservation Organization, 1964.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Soil and Water. National Water and Soil Conservation Organization, 1964.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.