References

        

  1. Bayard, Frederick. (1981) The Oxford Encyclopedia of Trees of the World. Oxford, NY: Oxford University Press
  2. Braham, Richard. (2002) North American Trees. Ames, IA: Iowa State Press
  3. Cafferty, Steve. (2005) Firefly Encyclopedia of Trees. Buffalo, NY: Firefly Books
  4. Gilman, E., Watson, D. (1994) “Picea abies: Norway Spruce,” Fact Sheet ST-448 of the U.S. Forest Service. Gainsville, FL: Institute of Food and Agriculture Sciences
  5. Plants Profile for Picea abies: Norway Spruce. Kartesz, John. USDA National Resources Conservation Service. 3/25/09 <http://plants.usda.gov/java/profile?symbol=PIAB&photoID=
    piab_003_ahp.tif>