Schiffman, S. (2008). The 25 sales skills they don`t teach at business school. massachusetts Adams Media Corp.
Chicago-referens (17:e uppl.)Schiffman, Stephan. The 25 Sales Skills They Don`t Teach at Business School. [s.l]: massachusetts Adams Media Corp, 2008.
MLA-referens (9:e uppl.)Schiffman, Stephan. The 25 Sales Skills They Don`t Teach at Business School. massachusetts Adams Media Corp, 2008.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.