Feld, W. J., & Boyd, G. (1980). Comparative regional systems: West and East Europe, North America, the Middle East, and developing countries. Pergamon Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रFeld, Werner J., और Gavin;Feld Boyd. Comparative Regional Systems: West and East Europe, North America, the Middle East, and Developing Countries. Pergamon Press, 1980.
एमएलए (9वां संस्करण) प्रशस्ति पत्रFeld, Werner J., और Gavin;Feld Boyd. Comparative Regional Systems: West and East Europe, North America, the Middle East, and Developing Countries. Pergamon Press, 1980.
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