Elliott, Deborah. Anon.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.

Iniguez, Jose M. Anon.2006. Landscape Fire History and Age Structure Patterns in the Sky Islands of Southeastern Arizona. School of Natural Resources. School of Natural Resources. University of Arizona. http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=1144189411&sid=5&Fmt=2&clientId=43922&RQT=309&VName=PQD.

Bristow, Katherine Jan Hansen. Anon.1981. Environmental Controls Influencing the Altitude and From of the Forest-Alpine Tundra Ecotone, Colorado Front Range. University of Colorado. http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=753126171&sid=5&Fmt=2&clientId=43922&RQT=309&VName=PQD.