The left and music

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Across
  1. 3. Wrote I was only 19
  2. 6. Famous Soviet composer
  3. 7. One of the most well known songs of the union movement
Down
  1. 1. Sung at the Sydney Opera house before it opened
  2. 2. Wrote Lads of the BLF
  3. 4. Alive as you and me
  4. 5. Famous German playwright and composer
  5. 8. Anthem of the working class