No documentation about Contacts and the API? Cannot import contacts! Help?

No documentation about Contacts and the API? Cannot import contacts! Help?

We have a client that uses Zoho for their business and they wish to use our software for sending out e-mails to their contact database. But I've looked through and through the entire Zoho documentation and not a single place actually lists 'Contacts'. Is it not possible to actually do anything with contacts through Zoho API?

By documentation, I mean the following:  https://apihelp.wiki.zoho.com/Zoho-API-Developers-Guide.html

I did find some mentions of Contacts in relation to Zoho API through Google, but nothing that actually solved my problem. 

I tried to make an API request to this URL: https://crm.zoho.com/crm/private/xml/Contacts/getRecords - which is totally undocumented in API documentation itself as 'crm.zoho.com' is not listed here  https://apihelp.wiki.zoho.com/Data-API-Reference.html as an accepted service name, but it was referenced in Google. But this gives me a response of 4834 Invalid Ticket Id.

Which brings me to tickets, what ticket do I need to actually make such a request? None of the tickets here  https://apihelp.wiki.zoho.com/Request-a-Ticket.html worked, even though it returned tickets every time.

Is Zoho API documentation entirely incomplete or am I missing something?