Madonna has paid tribute to 70s pop superstars Abba, in the sleevenotes for their new Greatest Hits album. The MATERIAL GIRL credits the Swedish fourpiece with inspiring her and a generation of artists. She writes, "Abba's timeless music continues to inspire me. It's joyous. Standing still when you hear Abba is impossible. "When I started recording my CONFESSIONS ON A DANCE FLOOR album, Stuart Price (producer) and I played their music constantly. "HUNG UP is my homage to their contribution to their music."