http://environment.nationalgeographic.com/environment/habitats/tundra-profile/
http://www.ucmp.berkeley.edu/glossary/gloss5/biome/tundra.html
http://www.softschools.com/facts/biomes/tundra_biome_facts/171/
http://www.ri.net/schools/West_Warwick/manateeproject/Tundra/Land.htm
http://www.arcticworld.net/tundra.htm
http://www.answers.com/Q/What_are_the_biotic_and_abiotic_factors_in_a_tundra
http://traveltips.usatoday.com/places-interest-tundra-15301.html
http://vault.sierraclub.org/habitat/esa/grizzly-bear.aspx
http://jeremy-buchanan.blogspot.com/2011/12/limiting-factors.html
http://www.marietta.edu/~biol/biomes/alpine.htm
http://www.blueplanetbiomes.org/tundra_plant_page.htm
http://www.blueplanetbiomes.org/tundra_animal_page.htm
http://sora.unm.edu/sites/default/files/journals/auk/v100n03/p0747-p0749.pdf
https://sites.google.com/site/arcticfoxstegenga/blog-page/blog-1
http://elainebp3.weebly.com/relationships--conservation.html
http://www.britannica.com/EBchecked/topic/608909/tundra/302379/Effects-of-human-activities-and-climate-change
http://www.ucmp.berkeley.edu/glossary/gloss5/biome/tundra.html
http://www.softschools.com/facts/biomes/tundra_biome_facts/171/
http://www.ri.net/schools/West_Warwick/manateeproject/Tundra/Land.htm
http://www.arcticworld.net/tundra.htm
http://www.answers.com/Q/What_are_the_biotic_and_abiotic_factors_in_a_tundra
http://traveltips.usatoday.com/places-interest-tundra-15301.html
http://vault.sierraclub.org/habitat/esa/grizzly-bear.aspx
http://jeremy-buchanan.blogspot.com/2011/12/limiting-factors.html
http://www.marietta.edu/~biol/biomes/alpine.htm
http://www.blueplanetbiomes.org/tundra_plant_page.htm
http://www.blueplanetbiomes.org/tundra_animal_page.htm
http://sora.unm.edu/sites/default/files/journals/auk/v100n03/p0747-p0749.pdf
https://sites.google.com/site/arcticfoxstegenga/blog-page/blog-1
http://elainebp3.weebly.com/relationships--conservation.html
http://www.britannica.com/EBchecked/topic/608909/tundra/302379/Effects-of-human-activities-and-climate-change