APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

Willis, Sherry L., and Mike Martin. Middle?adulthood?: A Lifespan Perspective. Thousand Oaks, Calif: SAGE Publications, 2005.

MLA (9th ed.) Citation

Willis, Sherry L., and Mike Martin. Middle?adulthood?: A Lifespan Perspective. SAGE Publications, 2005.