Dyfyniad APA

Lutgens, K. F., & Tarbuck, E. J. (1989). Essentials of geology/3rd ed (3rd ed.). Merrill.

Dyfyniad Arddull Chicago

Lutgens, K. Frederick, and Edward J. Tarbuck. Essentials of Geology/3rd Ed. 3rd ed. London: Merrill, 1989.

Dyfyniad MLA

Lutgens, K. Frederick, and Edward J. Tarbuck. Essentials of Geology/3rd Ed. 3rd ed. Merrill, 1989.

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