Greenberg, P. (2010). CRM (Customer Relationship Management) at the Speed of Light (4th.). Tata McGraw Hill Education Private Limited.
Chicago-viite (17. p.)Greenberg, Paul. CRM (Customer Relationship Management) at the Speed of Light. 4th. New Delhi: Tata McGraw Hill Education Private Limited, 2010.
MLA-viite (9. p.)Greenberg, Paul. CRM (Customer Relationship Management) at the Speed of Light. 4th. Tata McGraw Hill Education Private Limited, 2010.
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