SCHIFFMAN STEPHAN. (2005). 25 SALES HABITS OF HIGHLY SUCCESSFUL SALESPEOPLE. ADAMS MEDIA CORPORATION.
Chicago-referens (17:e uppl.)SCHIFFMAN STEPHAN. 25 SALES HABITS OF HIGHLY SUCCESSFUL SALESPEOPLE. MASSACHUETTS: ADAMS MEDIA CORPORATION, 2005.
MLA-referens (9:e uppl.)SCHIFFMAN STEPHAN. 25 SALES HABITS OF HIGHLY SUCCESSFUL SALESPEOPLE. ADAMS MEDIA CORPORATION, 2005.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.