Cita APA (7th ed.)

Eugene, T., & Fisher, R. (2003). Hiking America's geology. National Geographic.

Cita Chicago (17th ed.)

Eugene, Toni, i Ron Fisher. Hiking America's Geology. Washington, D.C: National Geographic, 2003.

Cita MLA (9th ed.)

Eugene, Toni, i Ron Fisher. Hiking America's Geology. National Geographic, 2003.