Though ABBA's massive hits eclipse the other material on their albums, the band's lesser-known songs still feel like potential anthems. Musical masterminds Benny Andersson and Björn Ulvaeus incorporate strands of disco, glam rock and musical theatre into their vision of pop, but when Agnetha Fältskog and Anni-Frid Lyngstad start to sing these golden hooks, the songs truly take flight.