Cita APA (7a ed.)

Sellers, M. (2007). The Funnel principle: What every salesperson must know about selling. Breakthrough SalesPerformance.

Cita Chicago Style (17a ed.)

Sellers, Mark. The Funnel Principle: What Every Salesperson Must Know About Selling. [Estats Units]: Breakthrough SalesPerformance, 2007.

Cita MLA (9a ed.)

Sellers, Mark. The Funnel Principle: What Every Salesperson Must Know About Selling. Breakthrough SalesPerformance, 2007.