Cita APA (7th ed.)

Levin, H. L. (1999). The Earth through time (6th ed.). Fort Worth : Saunders College Pub.

Cita Chicago (17th ed.)

Levin, Harold L. The Earth Through Time. 6th ed. Fort Worth : Saunders College Pub, 1999.

Cita MLA (9th ed.)

Levin, Harold L. The Earth Through Time. 6th ed. Fort Worth : Saunders College Pub, 1999.