function prepareGallery(){
  if( document.getElementById &&
      document.getElementsByTagName ){
    if( document.getElementById( 'referenz_galerie' ) ){
      var gallery = document.getElementById( 'referenz_galerie' );
      var links = gallery.getElementsByTagName( 'a' );
      for( var i=0; i < links.length; i++ ){
        links[i].onclick = function(){
          return showPic(this);
        };
      }
    }
  }
}

function showPic (whichpic) {
 if (document.getElementById) {
  document.getElementById('referenz_foto').src = whichpic.href;
  return false;
 } else {
  return true;
 }
}

function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent(prepareGallery);