Set user's sub calendar in Outlook 2013 to read only

We are sharing a Public Calendar with a user by pushing the data from the Public Calendar to a sub calendar under the user's calendar in Outlook 2013 (via Exchange 2010 and CodeTwo Exchange Sync). We would like to make this sub calendar read only to the user. Is any way to make this calendar read only so the user can view the entries but not change them?

David