Hopkins, T. (1982). How to master the art of selling. Warner Books.
Cita Chicago (17th ed.)Hopkins, Tom. How to Master the Art of Selling. New York: Warner Books, 1982.
Cita MLA (9th ed.)Hopkins, Tom. How to Master the Art of Selling. Warner Books, 1982.
Atenció: Aquestes cites poden no estar 100% correctes.