http://environment.nationalgeographic.com/environment/habitats/tundra-profile/
http://answers.yahoo.com/question/index?qid=20081005173730AADPOMy
http://answers.yahoo.com/question/index;_ylt=Auqb6UTwnSzxkNFvORHVJekjzKIX;_ylv=3?qid=20100324083445AAwQq5khttp://www.ask.com/Q/do-walruses-live-in-the-tundra
http://books.google.com/books?id=Amxq0Iz_kSoC&pg=PA55&dq=what+would+happen+if+lemmings+were+removed+from+the+arctic+ecosystem&hl=en&sa=X&ei=OrsrUY3rOYeSqwGHjYHoBg&sqi=2&ved=0CEkQ6AEwBQ#v=onepage&q=what%20would%20happen%20if%20lemmings%20were%20removed%20from%20the%20arctic%20ecosystem&f=false
yalescientific.org
http://www.windows2universe.org/earth/polar/arctic_tundra.html
http://answers.yahoo.com/question/index?qid=20081005173730AADPOMy
http://answers.yahoo.com/question/index;_ylt=Auqb6UTwnSzxkNFvORHVJekjzKIX;_ylv=3?qid=20100324083445AAwQq5khttp://www.ask.com/Q/do-walruses-live-in-the-tundra
http://books.google.com/books?id=Amxq0Iz_kSoC&pg=PA55&dq=what+would+happen+if+lemmings+were+removed+from+the+arctic+ecosystem&hl=en&sa=X&ei=OrsrUY3rOYeSqwGHjYHoBg&sqi=2&ved=0CEkQ6AEwBQ#v=onepage&q=what%20would%20happen%20if%20lemmings%20were%20removed%20from%20the%20arctic%20ecosystem&f=false
yalescientific.org
http://www.windows2universe.org/earth/polar/arctic_tundra.html