Não informado. (1941). Crop Production. Department of Agriculture, Statistical Reporting Service.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Crop Production. Washington: Department of Agriculture, Statistical Reporting Service, 1941.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Crop Production. Department of Agriculture, Statistical Reporting Service, 1941.
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