Related Clues:

• Group whose first U.S. hit was 'Waterloo'
• Did Poe rue being on the continent?
• Pop group once providing their own backing
• ''Mamma Mia!'' pop group
• 'Mamma Mia' band
• 'Bang-A-Boomerang' band
• 'SOS' quartet
• Quartet whose name is made up of its members' initials
• Group who, according to urban legend, knew no English but phonetically learned the lyrics to all their songs
• Band whose music was the basis for 'Mamma Mia!'
• Quartet with its own Stockholm museum
• "SOS" group
• Two of its members wrote the music for "Chess"
• 'Take A Chance On Me' group
• Group heard in ''Mamma Mia!''