Sibley, D. (2009). The Sibley guide to trees. New York: Alfred A. Knopf. 49.
Sibley, David. The Sibley Guide to Trees. New York: Alfred A. Knopf, 2009. Print. 99.
Sibley, David. The Sibley Guide to Trees. New York: Alfred A. Knopf, 2009. Print. 99.