function referencja(nr_ref) {
        advAJAX.setDefaultParameters({
          onInitialization : function(obj) { document.getElementById(obj.tag).innerHTML = "Preparing..."; },
          onLoading : function(obj) { document.getElementById(obj.tag).innerHTML = "Ładowanie danych..."; },
          onSuccess : function(obj) { document.getElementById(obj.tag).innerHTML = obj.responseText; },
          onError : function(obj) { document.getElementById(obj.tag).innerHTML = "Error..."; }
        });
       	document.getElementById('nr_ref').style.visibility="visible";
        advAJAX.get({ url: "listy_ref.php?nr_ref="+nr_ref, tag: "nr_ref" });
        advAJAX.setDefaultParameters({});
	}
	function hide_referencja() {
		document.getElementById('nr_ref').style.visibility="hidden";
	}