engert, m. (1964). classification of industries in social countries. the institute of national planning.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रengert, manfred. Classification of Industries in Social Countries. cairo: the institute of national planning, 1964.
एमएलए (9वां संस्करण) प्रशस्ति पत्रengert, manfred. Classification of Industries in Social Countries. the institute of national planning, 1964.
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