Pickering, G. W. (1967). The challenge to education. Watts.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPickering, George White. The Challenge to Education. London: Watts, 1967.
एमएलए (8वां संस्करण) प्रशस्ति पत्रPickering, George White. The Challenge to Education. Watts, 1967.
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