Swedish singer's Bjorn Ulvaeus, left, and Anni-Frid Lyngstad, of the pop group ABBA, pose on the red carpet ahead of the band's International anniversary party at the Tate Modern in central London, ... more 
Swedish singer's Bjorn Ulvaeus, left, and Anni-Frid Lyngstad, of the pop group ABBA, pose on the red carpet ahead of the band's International anniversary party at the Tate Modern in central London, Monday, April 7, 2014. The event marks the launch of ABBA – The Official Photo Book, the first ever authorised photographic biography of the band. (Photo by Joel Ryan/Invision/AP Images) less 
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Associated Press
Mon, Apr 7, 2014 4:57 PM EDT