Dyfyniad APA

Ojakangas, R. W., & Darby, D. G. (1976). The earth: :Past and present. Mc Graw Hills.

Dyfyniad Arddull Chicago

Ojakangas, Richard W., and David G. Darby. The Earth: :Past and Present. New York: Mc Graw Hills, 1976.

Dyfyniad MLA

Ojakangas, Richard W., and David G. Darby. The Earth: :Past and Present. Mc Graw Hills, 1976.

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