Dyfyniad APA

Gilluly, J., Waters, A. C., & Woodford, A. O. (1975). Principles of geology (4th ed.). W. H. Freeman.

Dyfyniad Arddull Chicago

Gilluly, James, Aaron Clement Waters, and Alfred O. Woodford. Principles of Geology. 4th ed. San Francisco: W. H. Freeman, 1975.

Dyfyniad MLA

Gilluly, James, et al. Principles of Geology. 4th ed. W. H. Freeman, 1975.

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