text: --- #dep loc-mds-index-books
  --- #dep gr-index-books
  --- #dep ol-index
  
  --- #step Extract normalized ISBNs
  DROP TABLE IF EXISTS isbn_norm CASCADE;
  CREATE TABLE isbn_norm (
      isbn_id INTEGER PRIMARY KEY,
      norm_isbn EAN13 NOT NULL
  );
  INSERT INTO isbn_norm
  SELECT isbn_id, make_valid(isbn(isbn || '!'))
  FROM isbn_id WHERE isbn ~ '^\d{9}[\dxX]$';
  INSERT INTO isbn_norm
  SELECT isbn_id, make_valid(ean13(regexp_replace(isbn, '[xX]$', '0') || '!'))
  FROM isbn_id WHERE isbn ~ '^9\d{11}[\dxX]$';