Get query string in a Sharepoint 2010 page through SP Services

<script src="../../JQuery/jquery-1.4.2.min.js" type="text/javascript"></script>
<script src="../../JQuery/jquery.SPServices-0.5.4.js" type="text/javascript"></script>

<script type="text/javascript">
$(document).ready(function(){

    var queryStringValues = $().SPServices.SPGetQueryString();
    var id = queryStringValues["ID"];
    var source= queryStringValues["Source"];
    alert(id);
    alert(source);
});


</script>