APA-referens (7:e uppl.)
Levy, S. (2011). Once & future giants: What Ice Age extinctions tell us about the fate of earth's largest animals. Oxford University Press.
Chicago-referens (17:e uppl.)
Levy, Sharon. Once & Future Giants: What Ice Age Extinctions Tell Us About the Fate of Earth's Largest Animals. Oxford ; New York: Oxford University Press, 2011.
MLA-referens (9:e uppl.)
Levy, Sharon. Once & Future Giants: What Ice Age Extinctions Tell Us About the Fate of Earth's Largest Animals. Oxford University Press, 2011.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.