Cita APA (7a ed.)

Levin, H. L. (1978). Study manual for the earth througt time. W. B. Saunders.

Cita Chicago Style (17a ed.)

Levin, Harold Leonard. Study Manual for the Earth Througt Time. Philadelphia, P.A.: W. B. Saunders, 1978.

Cita MLA (8a ed.)

Levin, Harold Leonard. Study Manual for the Earth Througt Time. W. B. Saunders, 1978.