Picture taken in 1974 in Stockholm shows the Swedish pop group Abba with its members (L-R) Benny Andersson, Anni-Frid Lyngstad, Agnetha Faltskog and Bjorn Ulvaeus posing after winning the Swedish branch of the Eurovision Song Contest with their song "Waterloo". – Sweden's legendary disco group ABBA announced on April 27, 2018 that they have reunited to record two new songs, 35 years after their last single. The quartet split up in 1982 after dominating the disco scene for more than a decade with hits like "Waterloo", "Dancing Queen", "Mamma Mia" and "Super Trouper". (Photo by Olle LINDEBORG / TT News Agency / AFP) / Sweden OUT (Photo credit should read OLLE LINDEBORG/AFP via Getty Images)
American pop and soul trio, Hues Corporation, performing on stage, July 1974. Left to right: Fleming Williams (1943 – 1992), Hubert Ann Kelley and St. Clair Lee (1944 – 2011). (Photo by Michael Putland/Getty Images)
NEW YORK – CIRCA 1975: Disco songwriter, producer and artist Van McCoy poses for a portrait circa 1975 in New York city, New York. (Photo by Michael Ochs Archives/Getty Images)
American singer Debbie Harry performing with Blondie at the Dr. Pepper Central Park Music Festival at Wollman Rink in Central Park, New York City, 9th July 1979. (Photo by Michael Putland/Getty Images)
Australian singer and actress Olivia Newton-John and American actor John Travolta as they appear in the Paramount film 'Grease', 1978. (Photo by Paramount Pictures/Fotos International/Getty Images)
NEW YORK – JANUARY 09: Maurice Gibb, Barry Gibb and Robin Gibb of The Bee Gees harmonise at one microphone while performing on stage at the UNICEF A Gift of Song concert held at the United Nations General Assembly on January 9th 1979 in New York. (Photo by Richard E. Aaron/Redferns)
David Bowie Performs On English Rock & Pop musician and actor David Bowie (born David Jones, 1947 – 2016) performs on stage, Los Angeles, California, 1975. (Photo by Ellen Graham/Getty Images)
