National Geographic Society. (2003). Grand canyon. Paris: National Geographic Explorer.
शिकागो स्टाइल उद्धरणNational Geographic Society. Grand Canyon. Paris: National Geographic Explorer, 2003.
एमएलए उद्धरणNational Geographic Society. Grand Canyon. Paris: National Geographic Explorer, 2003.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.