Cita APA (7a ed.)

LEVIN, H. L. (1983). The earth through time.-- ed.2. Saunders College.

Cita Chicago Style (17a ed.)

LEVIN, Harold L. The Earth Through Time.-- Ed.2. New York: Saunders College, 1983.

Cita MLA (9a ed.)

LEVIN, Harold L. The Earth Through Time.-- Ed.2. Saunders College, 1983.