function createResources() {
    if( 0 >= count( $this->resources ))
      return;
    $output = null;
    foreach( $this->resources as $resource ) {
      $attributes = $this->_createParams( $resource['params'], array( 'ALTREP', 'LANGUAGE' ));
      if( is_array( $resource['value'] )) {
        foreach( $resource['value'] as $rix => $resourcePart )
          $resource['value'][$rix] = $this->_strrep( $resourcePart );
        $content  = implode( ',', $resource['value'] );
      }
      else
        $content  = $this->_strrep( $resource['value'] );
      $output    .= $this->_createElement( 'RESOURCES', $attributes, $content );
    }
    return $output;
  }