Hart, R. D. An ecological systems conceptual framework for agricultural research and development.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रHart, Robert D. An Ecological Systems Conceptual Framework for Agricultural Research and Development. [Date of publication not identified].
एमएलए (9वां संस्करण) प्रशस्ति पत्रHart, Robert D. An Ecological Systems Conceptual Framework for Agricultural Research and Development.
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