Dyfyniad APA

Orr, E. L., & Orr, W. L. (1996). Geology of the Pacific Northwest. McGraw-Hill.

Dyfyniad Arddull Chicago

Orr, Elizabeth L., and William L. Orr. Geology of the Pacific Northwest. New York: McGraw-Hill, 1996.

Dyfyniad MLA

Orr, Elizabeth L., and William L. Orr. Geology of the Pacific Northwest. McGraw-Hill, 1996.

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