Coxhead, I. A. (1991). Environmental specific rates and biases of technical change in agriculture. s.n.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रCoxhead, Ian A. Environmental Specific Rates and Biases of Technical Change in Agriculture. [S.l: s.n, 1991.
एमएलए (9वां संस्करण) प्रशस्ति पत्रCoxhead, Ian A. Environmental Specific Rates and Biases of Technical Change in Agriculture. s.n, 1991.
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