[Koha] Circulation rule for Collection.

Hi, In our library, all the reference books are catalogued under the item type "Books"; no additional item type is defined for reference books. However, reference books are marked with a CCODE "Ref", So now I want to set up a circulation rule for reference books or all items where CCODE is flagged "ref" that they are restricted from checkout. is there any way to do that? Thanks in advance Rupinder Singh