Castaldo, N. F., De Seve, K., & Raven-Ellison, D. (2014). Mission: polar bear rescue: All about polar bears and how to save them. National Geographic Society.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रCastaldo, Nancy F., Karen De Seve, और Daniel Raven-Ellison. Mission: Polar Bear Rescue: All About Polar Bears and How to Save Them. Washington, D.C.: National Geographic Society, 2014.
एमएलए (8वां संस्करण) प्रशस्ति पत्रCastaldo, Nancy F., et al. Mission: Polar Bear Rescue: All About Polar Bears and How to Save Them. National Geographic Society, 2014.
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