APA (7th ed.) Citation

World Health Organization, Abou Zahr, C., & Royston, E. (1991). Maternal mortality: A global factbook. World Health Organization.

Chicago Style (17th ed.) Citation

World Health Organization, Carla Abou Zahr, and Erica Royston. Maternal Mortality: A Global Factbook. Geneva: World Health Organization, 1991.

MLA (9th ed.) Citation

World Health Organization, et al. Maternal Mortality: A Global Factbook. World Health Organization, 1991.