References

References

 

Woolverton et al. Arctic Tale. National Geographic, 2007.

Curtsinger, Bill. Naturaleza al extremo. Numen, 2005.

Enciclopedia del mundo animal. Parragon, 2013. Pp. 18-19.

Alderton, David. The encyclopedia of animals. Chartwell books, Inc., 2009. Pág. 170

Sale, Richard. The Arctic. The complete story. Frances Lincoln Limited Publishers, 2008. Pp. 446-450.

Animals, a visual encyclopedia. Smithsonian. 2012. Pp. 17, 64, 65.

World of animals. Book of predators. Imagine publishing, 2014. Pp. 55-63.

http://animaldiversity.org/accounts/Ursus_maritimus/

https://www.savethearctic.org/

http://www.nwf.org/wildlife/wildlife-library/mammals/polar-bear.aspx

http://www.worldwildlife.org/species/polar-bear

http://www.polarbearsinternational.org/about-polar-bears

http://en.wikipedia.org/wiki/Polar_bear