MLA

Downey, Scott, et al. The Core of Professional Selling. USA, 2012.

APA

Downey, S., Downey, D., Jackson, M., & Downey, L. (2012). The core of professional selling. USA.

Chicago

Downey, Scott, David Downey, Mike Jackson, and Laura Downey. The Core of Professional Selling. USA, 2012.