Zeylstra, W. G. (1975). Aid or development: The relevance of development aid to problems of developing countries. A.W. Sijthoff.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रZeylstra, Willem Gustaaf. Aid or Development: The Relevance of Development Aid to Problems of Developing Countries. Leyden: A.W. Sijthoff, 1975.
एमएलए (9वां संस्करण) प्रशस्ति पत्रZeylstra, Willem Gustaaf. Aid or Development: The Relevance of Development Aid to Problems of Developing Countries. A.W. Sijthoff, 1975.
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