Engert, M. (1969). Problems of Long-term Planning in the German Democratic Republic. The Institute of National Planning.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रEngert, Manfred. Problems of Long-term Planning in the German Democratic Republic. Cairo: The Institute of National Planning, 1969.
एमएलए (9वां संस्करण) प्रशस्ति पत्रEngert, Manfred. Problems of Long-term Planning in the German Democratic Republic. The Institute of National Planning, 1969.
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