gistfile1.txt

function add_attribution_backlink( $content ) {
  // Process content here and add the backlink
  
  $backlink = ‘<div class=”attribution”>This article first appeared on <a href=”http://premium.wpmudev.org/blog”>WPMU Dev Blog</a></div>’;

  $content = $content . $backlink;
  return $content;
}

add_filter( 'content_save_pre', ‘add_attribution_backlink’, 10, 1 );