window.addEvent('domready', function() {
  if ($$('.referenz_img_thumb') != null) {
    $$('.referenz_img_thumb').addEvent('click', function(e) {
        e.stop();
        $$('.referenz_img_thumb').removeClass('referenz_img_thumb_outline');
        this.addClass('referenz_img_thumb_outline');
    });
    document.getElementById('referenz_img_tag').src = document.getElementById('referenz_img_tag_1').src;
  }
});