Birdsall, S. S., & Florin, J. (1992). Outline of American Geography. New York: John Wiley & Sons.
Chicago Style aipamenaBirdsall, Stephen S., và John Florin. Outline of American Geography. New York: John Wiley & Sons, 1992.
MLA aipamenaBirdsall, Stephen S., và John Florin. Outline of American Geography. New York: John Wiley & Sons, 1992.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.