Orr, E. L., & Orr, W. L. (1996). Geology of the Pacific Northwest. McGraw-Hill.
Chicago Style aipamenaOrr, Elizabeth L., and William L. Orr. Geology of the Pacific Northwest. New York: McGraw-Hill, 1996.
MLA aipamenaOrr, Elizabeth L., and William L. Orr. Geology of the Pacific Northwest. McGraw-Hill, 1996.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.