Panikkar, K. M. (1959). Geographical factors in Indian history (2nd.). Bharatiya Vidya Bhavan.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPanikkar, Kavalam Madhava. Geographical Factors in Indian History. 2nd. Bharatiya Vidya Bhavan, 1959.
एमएलए (9वां संस्करण) प्रशस्ति पत्रPanikkar, Kavalam Madhava. Geographical Factors in Indian History. 2nd. Bharatiya Vidya Bhavan, 1959.
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