Deirdre Heenan/ Derek Birrell
(3)
Ann Marie Gray/ Derek Birrell
(2)
Derek Birrell/ Ann Marie Gray
(2)
Paul (The University of Ulster Carmichael UK),Derek (The University of Ulster Birrell UK),Deirdre (The University of Ulster Heenan UK)
(2)
Derek Birrell/ Cathy Gormley-heenan
(1)