APA (7th ed.) Citation

Rocky Mountain Association of Geologists, Kent, H. C., & Porter, K. W. (1980). Colorado geology. Rocky Mountain Association of Geologists.

Chicago Style (17th ed.) Citation

Rocky Mountain Association of Geologists, Harry C. Kent, and Karen W. Porter. Colorado Geology. Denver: Rocky Mountain Association of Geologists, 1980.

MLA (9th ed.) Citation

Rocky Mountain Association of Geologists, et al. Colorado Geology. Rocky Mountain Association of Geologists, 1980.