International Council for Correspondence Education. World Conference & Wentworth, R. B. (1978). Correspondence education, dynamic and diversified: Eleventh World Conference, Hotel Ashoka, New Delhi, India, 8-15 November 1978. s.n..
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रInternational Council for Correspondence Education. World Conference और Robert B. Wentworth. Correspondence Education, Dynamic and Diversified: Eleventh World Conference, Hotel Ashoka, New Delhi, India, 8-15 November 1978. [s.l.: s.n., 1978.
एमएलए (8वां संस्करण) प्रशस्ति पत्रInternational Council for Correspondence Education. World Conference और Robert B. Wentworth. Correspondence Education, Dynamic and Diversified: Eleventh World Conference, Hotel Ashoka, New Delhi, India, 8-15 November 1978. s.n., 1978.
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