External CRMs integration with Zoho system

External CRMs integration with Zoho system

Hey guys, now we are observing Zoho CRM service to configure it for ur company and our clients (B2B, B2C clients). We want to change business model to shared model and want to have the ability to integrate CRMs of our clients into Zoho CRM in order to have all in one place (not all data from client's CRM will be synch with Zoho CRM). CRM of our clients  have mostly the same structure. Is it possible or not? If so, what documentation should we research to start integrations?