Não informado. (1949). Abstracts of recent published material on soil and water conservation. Agricultural Research Service, Soil and Water Conservation Division.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Abstracts of Recent Published Material on Soil and Water Conservation. Washington: Agricultural Research Service, Soil and Water Conservation Division, 1949.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Abstracts of Recent Published Material on Soil and Water Conservation. Agricultural Research Service, Soil and Water Conservation Division, 1949.
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