APA (7th ed.) Citation

National Geographic Maps (Firm), Carroll, A., Shupe, J. F., Berry, C. W., & Pratt, R. E. (1997). The Roman Empire. National Geographic Society.

Chicago Style (17th ed.) Citation

National Geographic Maps (Firm), Allen Carroll, John F. Shupe, Charles W. Berry, and Robert E. Pratt. The Roman Empire. Washington, D.C.: National Geographic Society, 1997.

MLA (9th ed.) Citation

National Geographic Maps (Firm), et al. The Roman Empire. National Geographic Society, 1997.