APA
(1997). Guns, Germs, and Steel. New York: W. W. Norton & Company.
Chicago
1997. Guns, Germs, and Steel. New York: W. W. Norton & Company.
Harvard
(1997). Guns, Germs, and Steel. New York: W. W. Norton & Company.
MLA
Guns, Germs, and Steel. New York: W. W. Norton & Company. 1997.