Dyfyniad APA

Levin, H. L. (1983). The earth through time (2nd ed.). Saunders College Pub..

Dyfyniad Arddull Chicago

Levin, Harold L. The Earth Through Time. 2nd ed. Philadelphia: Saunders College Pub., 1983.

Dyfyniad MLA

Levin, Harold L. The Earth Through Time. 2nd ed. Saunders College Pub., 1983.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.