Location of Contacts Server Files

Hi,

Where are the files placed on the server when a user creates/imports/manages their Contacts on a Mountain Lion Server Contacts Server?

Example: I have a Mountain Lion Server running the latest 10.8.2 updates with Contacts sharing turned on in the Server app.

Client user on another machine adds the server to their Contacts book and begins putting contacts into their account, creating groups on the server and placing contacts into those groups.

I want to back this up on the server side of things, so that I don't need access to all the clients.

Thanks in advance.