query: SELECT ?item ?value WHERE
  {
    ?item p:P973/ps:P973 ?value .
    
    FILTER( REGEX(REPLACE(STR(?value), "%20", " "), "^(https?://catalogue\\.bnf\\.fr/ark:/12148/cb((\\d{8}[0-9bcdfghjkmnpqrstvwxz])))$") )
  }