Mandino, O. (1968). The greatest salesman in the world. Frederick Fell.
Cita Chicago (17th ed.)Mandino, Og. The Greatest Salesman in the World. New York: Frederick Fell, 1968.
Cita MLA (9th ed.)Mandino, Og. The Greatest Salesman in the World. Frederick Fell, 1968.
Atenció: Aquestes cites poden no estar 100% correctes.