Integration and Differentiation in the European UnionDirk Leuffen, Berthold Rittberger, Frank Schimmelfennig · First published 2021Open the Tome
Differentiated IntegrationDirk Leuffen, Berthold Rittberger, Frank Schimmelfennig · First published 2012Open the Tome
Differentiated Integration Explaining Variation In The European UnionDirk Leuffen · First published 2012Open the Tome
