Silva, M. e. (1972). 1973 Britannica yearbooks of science and the future. Encyclopaedia Britannica.
शिकागो स्टाइल उद्धरणSilva, Michel ed. 1973 Britannica Yearbooks of Science and the Future. Chicago: Encyclopaedia Britannica, 1972.
एमएलए उद्धरणSilva, Michel ed. 1973 Britannica Yearbooks of Science and the Future. Encyclopaedia Britannica, 1972.
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