Cita APA (7a ed.)

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

Cita Chicago Style (17a ed.)

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

Cita MLA (9a ed.)

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