galerie Willy Schoots #JOOP BIRKER # 1988, mint-
galerie Witt # JOOP BIRKER # 1991, nm
galerie Hüsstege # JOOP BIRKER / MIKULAS RACHLIK #invitation, 1991, mint-
galerie Willy Schoots # JOOP BIRKER # invitation, 1988, nm+