APA (7th ed.) Citation

Willis, S. L., & Martin, M. (2005). Middle adulthood: A lifespan perspective. Sage.

Chicago Style (17th ed.) Citation

Willis, Sherry L., and Mike Martin. Middle Adulthood: A Lifespan Perspective. Thousand Oaks, California: Sage, 2005.

MLA (9th ed.) Citation

Willis, Sherry L., and Mike Martin. Middle Adulthood: A Lifespan Perspective. Sage, 2005.