APA (7th ed.) Citation

Adams, A., Stillman, A. G., & Turnage, W. A. (1992). Our national parks. Little, Brown.

Chicago Style (17th ed.) Citation

Adams, Ansel, Andrea Gray Stillman, and William A. Turnage. Our National Parks. Boston: Little, Brown, 1992.

MLA (9th ed.) Citation

Adams, Ansel, et al. Our National Parks. Little, Brown, 1992.