function ChangeLang(lang) {
 	var sstring = location.search;
 	if (sstring != "")
 	{
 	  if (sstring.indexOf("lang=") > -1)
	 	{
	 	 	sstring=sstring.replace(/lang=de/, "lang="+lang);
	 	 	sstring=sstring.replace(/lang=en/, "lang="+lang);
	 	}
		else
	 		sstring += '&lang='+lang;
	}
 	else
 		sstring = '?lang='+lang;
 	window.location.replace(window.location.pathname+sstring);
}