Fraknoi, A., & Morrison, D. W. (2001). Voyages through the universe (2nd ed.). Harcourt College Publishers.
शिकागो स्टाइल उद्धरणFraknoi, Andrew, और David Wolff Morrison. Voyages Through the Universe. 2nd ed. Philadelphia: Harcourt College Publishers, 2001.
एमएलए उद्धरणFraknoi, Andrew, और David Wolff Morrison. Voyages Through the Universe. 2nd ed. Harcourt College Publishers, 2001.
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