What is CRM, https://www.salesforce.com/crm/what-is-crm/
CRM Software Demystified, https://crm.org/
Professional Sales Association, http://www.professionalsalesassociation.co.uk/
European Sales and Marketing Association, https://esma.org/
Sales Institute of Greece, https://ipe.org.gr/
Hellenic Direct Selling Association (HDSA), https://www.eseap.org.gr/
Hellenic Institute of Customer Service (EIEP), https://customerservice.gr/
Entrepreneur Handbook, https://entrepreneurhandbook.co.uk/what-is-customer-service/