Elliott, Deborah. 1979. ?The Stability Of The Northern Canadian Tree Limit: Current Regenerative Capacity?. Geography. Geography. University of Colorado. http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=751614031&sid=5&Fmt=1&clientId=43922&RQT=309&VName=PQD.