public function findSources(string $sources): array
  {
    $patterns = $this->sourcesToPatterns($sources);

    $sources = [];
    foreach ($patterns as $pattern)
    {
      $tmp     = $this->findSourcesInPattern($pattern);
      $sources = array_merge($sources, $tmp);
    }

    $sources = array_unique($sources);
    sort($sources);

    return $sources;
  }