forward only single zone

[Oto BREZINA]

I got successfuly set schizophrenic bind based DNS. It is version 9.9.5 
running on Ubuntu .

I got local zones :
     serving internal side.
     public zones master and slaves (server in same way for internal and 
externals clients)

I need to create one subzone of public zone which is served by another 
server. This can not be transfered. Server is located on LAN.
Is there way to set this? I tried to set views, but with no luck.

my setting right now is like:

view "local" {
         allow-query { internals; };
         match-clients { internals; };
         recursion yes;

         include "local zones";
         include "public zones";
         include "slave zones";
};

view "public" {
         allow-query { any; };
         match-clients { any; };
         recursion no;

         include "public zones"; // contains example.com with clue to 
same server
         include "slave zones";
};

I need to add

zone "calc.example.com" {
                 type forward;
                 forward only;
                 forwarders { local_machine; };
         };

adding it to local wont let external client to get access, but works 
from internals
adding it to public, does not help, it returns only clues; forward only 
wont word as recursion is no, adding another view public2 seems have no 
affect.

I'm aware it is not recomented setup, but even I would run separate 
local and public server, I have still no idea how have not open DNS but 
forward single zone.

Please advise.

Oto