Use REFERENCES in Vertical Fragmentation table in Oracle

First create the following tables in two different databases

Fragment1:
Employee(EID number(4)PRIMARY KEY, Name varchar2(20),Address varchar2(50));

Fragment2:
Employee(EID number(4),Dep_Id number(4),Mgr_Id REFERENCES Employee(EID),Salary number(6));

and then Create a trigger to insert data into appropriate table.

I am not able to use REFERENCE Employee(EID) [of Fragment 1] in Mgr_Id

Please Help