Balsam Fir Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Balsam_fir

Douglas Fir Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Douglas_fir

Fraser Fir Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Fraser_Fir

Pine Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Pine

Eastern White Pine Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Eastern_white_pine

Spruce Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Spruce

Blue Spruce Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Blue_spruce

Serbian Spruce Retrieved July 23, 2007, from http://en.wikipedia.org/wiki/Serbian_spruce

Balsam Fir Retrieved July 24, 2007, from http://www.nursery-plants.info/trees/subcat/windbreak/balsam_fir.html

Douglas Fir Retrieved July 24, 2007, from http://www.nursery-plants.info/trees/subcat/windbreak/douglas_fir.html

Fraser Fir Retrieved July 24, 2007, from http://www.nursery-plants.info/trees/subcat/windbreak/fraser_fir.html

Eastern White Pine Retrieved July 24, 2007, from http://www.nursery-plants.info/trees/subcat/windbreak/eastern_white_pine.html

Blue Spruce Retrieved July 24, 2007, from http://www.nursery-plants.info/trees/subcat/windbreak/colorado_blue_spruce.html