<script type="text/javascript">  
  function addLink() {  
  var element_body = document.getElementsByTagName('body')[0];  
  var selection;  
  selection = window.getSelection();  
  var linkpage = "<br/>Источник: <a href='"+document.location.href+"'>"+document.location.href+"</a>";  
  var copytext = selection + linkpage;  
  var divnew = document.createElement('div');  
  divnew.style.position='absolute';  
  divnew.style.left='-99999px';  
  element_body.appendChild(divnew);  
  divnew.innerHTML = copytext;  
  selection.selectAllChildren(divnew);  
  window.setTimeout(function() {  
  element_body.removeChild(divnew);  
  },0);  
}  
document.oncopy = addLink;  
</script>