Não informado. (1949). Abstracts of recent published material on soil and water conservation. Agricultural Research Service, Soil and Water Conservation Division.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Abstracts of Recent Published Material on Soil and Water Conservation. Washington: Agricultural Research Service, Soil and Water Conservation Division, 1949.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Abstracts of Recent Published Material on Soil and Water Conservation. Agricultural Research Service, Soil and Water Conservation Division, 1949.
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