Não informado. (1968). Foreign agriculture. U.S. Department of Agriculture, Foreign Agricultural Service.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Foreign Agriculture. Washington: U.S. Department of Agriculture, Foreign Agricultural Service, 1968.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Foreign Agriculture. U.S. Department of Agriculture, Foreign Agricultural Service, 1968.
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