Langford, P. (1987). Concept development in the primary school. Croom Helm.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रLangford, Peter. Concept Development in the Primary School. London ; New York: Croom Helm, 1987.
एमएलए (8वां संस्करण) प्रशस्ति पत्रLangford, Peter. Concept Development in the Primary School. Croom Helm, 1987.
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