KATZ BERNARD. (1987). HOW TO TURN CUSTOMER SERVICE IN TO CUSTOMER SALES. WILDWOOD HOUSE LTD.
Chicago-viite (17. p.)KATZ BERNARD. HOW TO TURN CUSTOMER SERVICE IN TO CUSTOMER SALES. ENGLAND: WILDWOOD HOUSE LTD, 1987.
MLA-viite (9. p.)KATZ BERNARD. HOW TO TURN CUSTOMER SERVICE IN TO CUSTOMER SALES. WILDWOOD HOUSE LTD, 1987.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.