query: SELECT ?item ?value WHERE
  {
    ?item p:P973/ps:P973 ?value .
    
    FILTER( REGEX(REPLACE(STR(?value), "%20", " "), "^(https?://(www\\.|beta\\.)?musicbrainz.org/artist/([0-9a-f]{8&#125;-[0-9a-f]{4&#125;-[0-9a-f]{4&#125;-[0-9a-f]{4&#125;-[0-9a-f]{12}))$") )
  }