Cita APA (7a ed.)

Penenberg, A. L. (2009). Viral loop: From Facebook to Twitter, how today's smartest businesses grow themselves. Tantor Media.

Cita Chicago Style (17a ed.)

Penenberg, Adam L. Viral Loop: From Facebook to Twitter, How Today's Smartest Businesses Grow Themselves. Old Saybrook: Tantor Media, 2009.

Cita MLA (9a ed.)

Penenberg, Adam L. Viral Loop: From Facebook to Twitter, How Today's Smartest Businesses Grow Themselves. Tantor Media, 2009.