APA aipamena

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

Chicago Style aipamena

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

MLA aipamena

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

Kontuz: berrikusi erreferentzia hauek erabili aurretik.