APA (7th ed.) Citation

National Geographic & Waring, R. (2009). Polar bears in trouble. National Geographic Learning.

Chicago Style (17th ed.) Citation

National Geographic and Rob Waring. Polar Bears in Trouble. Boston: National Geographic Learning, 2009.

MLA (9th ed.) Citation

National Geographic and Rob Waring. Polar Bears in Trouble. National Geographic Learning, 2009.

Warning: These citations may not always be 100% accurate.