Dyfyniad APA

National Geographic Society. (2000). Forces. New York: McGraw-Hill School Division.

Dyfyniad Arddull Chicago

National Geographic Society. Forces. New York: McGraw-Hill School Division, 2000.

Dyfyniad MLA

National Geographic Society. Forces. New York: McGraw-Hill School Division, 2000.

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