Asimov, I. (1989). Frontiers: New discoveries about man and his planet, outer space, and the universe. Truman Talley Books/Plume.
शिकागो स्टाइल उद्धरणAsimov, Isaac. Frontiers: New Discoveries About Man and His Planet, Outer Space, and the Universe. New York: Truman Talley Books/Plume, 1989.
एमएलए उद्धरणAsimov, Isaac. Frontiers: New Discoveries About Man and His Planet, Outer Space, and the Universe. Truman Talley Books/Plume, 1989.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.