Geographic variation in Pinus contorta

Chicago citation style
Critchfield, William Burke. Geographic variation in Pinus contorta. 1957. Retrieved from the Digital Public Library of America, http://catalog.hathitrust.org/Record/001662705. (Accessed November 21, 2018.)
APA citation style
Critchfield, William Burke, (1957) Geographic variation in Pinus contorta. Retrieved from the Digital Public Library of America, http://catalog.hathitrust.org/Record/001662705
MLA citation style
Critchfield, William Burke. Retrieved from the Digital Public Library of America <http://catalog.hathitrust.org/Record/001662705>.
Note: These citations are programmatically generated and may be incomplete.